Hey Ya'll,
We are dead on the side of the road outside of Guadalupe National Park in TX.
1987 Chevy P30 454 7.4L.
Can't get the coach to go forward... not sure why.
Here's what she does:
1 - Starts up
2 - Seems to idle low, if you give it a bit of gas it idles better.
3 - Let off the gas and let it idle for long enough, it'll shut off.
4 - If you put it in drive and push on the gas... the engine dies.
These sound like fuel starvation symptoms.
But, I literally just put in a brand new high performance holley blue fuel pump this afternoon.
I was having Vapor Lock issues when I'd idle in traffic or sit too long as a stop light or turn it off to get gas. The engine bay would get warmer and the pump wouldn't pump fuel (assuming cause it'd be pumping vapor). And the see through fuel filter I have under the doghouse by the carb would be dry.
So reading Chevy's service manual for that issue, they recommended upgrading the fuel pump to the Holley Electric Fuel Pump: https://www.summitracing.com/parts/hly-12-802-1
I installed that this afternoon cause the wimpy electric fuel pump that the PO installed finally gave out this afternoon. It's was an off the shelf auto-zone fuel pump. Don't think it was powerful enough for this coach anyways.
After installing the new pump, the coach started right up and we drove about 20 miles before the coach started getting warm (on a flat travel surface). It's never done that before. So we waited a while and tried again about 7 miles before we hit a grade. Made it about a mile up the grade before we started losing power (ie step on the gas and engine wouldn't rev, it would lose rpms) and it was getting warm again.
We have let it sit for a couple hours now and it'll still start. The new fuel pump is pumping fuel nicely (you can see it doing it's job in the clear fuel filter under the doghouse.
But when you start and put into drive and push on the gas, it shuts off like it's being fuel starved... and we start rolling back down the hill... which sucks.
Any ideas?
I've fixed damn near everything on this engine. It's got a brand new starter, brand new alternator, radiator has been checked and flushed, brand new fan clutch, new plugs, cap, rotor, & wires. New power steering pump. New brake master cylinder. New air filters. New Fuel filters.
I didn't adjust the carb or the new fuel pressure regulator after putting in the new fuel pump... 1, cause the holley pump instruction guide said you shouldn't have to and 2, cause I don't know how.
Could the pressure regulator be giving too much/little pressure and causing it to act like this?
Some questions: Are you plumbed though the original fuel pump? Does the carburetor have a brass filter behind where the fitting for the fuel line goes into it?
Another thought is you need to double check your timing. You may need to back off the timing (retard it some) this can help both with the heating and fuel trouble. Years ago this was a common thing we had trouble with going from the flat land up to the Colorado mountains. We would also stop along the way and change jets in the carb. but that is another thread.
Mike
Vacuum leak from a hose that got disturbed during install??? Smell the exhaust. Some carbs are extremely sensitive to fuel pressure. Overheat sounds like it may be too lean of gas mixture.
Hey
@craneman!
There is no brass filter behind where the fitting for the fuel line goes. Pic attached.
We are not plumbed through the original fuel pump. It appears to have been capped off or something and the fuel lines aren't in use.
These pics didn't attach on the last post.
How would I adjust the timing? Need any specialized tools to do it?
Hey Old Phart! Good to hear from you. :)
There are no vacuum hoses near the fuel pump as far as I can see. But then again, I'm not entirely sure how to tell if something is a vaccuum line. I thought those were the line running from the air box down into the engine.
I've heard that the carb could be sensitive to fuel pressure, how would I test or know if the carb is getting too much or too little pressure? I assume that it's now getting more pressure than it was before, since this pump is a much higher end pump than the one that I had in there before from the PO. I believe there is a simple screw adjustment on the holly regulator that will adjust the pressure if I need to.
And another question on that... if the pump is giving it too much fuel pressure... how would that result in too lean of a gas mixture? Seems like it'd be too rich.
Last question... smell the exhaust and look for what in the smells?
The filter I am referring to would be behind the fitting in the carburetor. Some Quadrajets came with them.
Also if you have too much fuel pressure it will push the fuel past the needle and seat and you would know as it would be flooding the engine. Volume is much more an issue with a carburetor.
Does your coach have a catalectic convertor? A plugged one would have all the symptoms you a are having.
Have you driven this before? or is this the first time running? Try taking the fuel cap off and see if it will run better.. Shortage of fuel it sounds like
My old P32 acted that way with a clogged fuel filter attached to the framerail.
Good point craneman, I forgot about those ity bitty tiny filters they used to install on the carb gas inlets. Also if you changed to a different pump make sure you did not pinch a line near the pump. It all goes back to the fire triangle fuel, oxygen, and ignition source.
@craneman - Attached is a pic inside the carb. The fuel comes in on the bottom right of the photo. Doesn't look like there is a filter.
And it sounds like I don't have a pressure issue.
I don't even know what one of those is. Lol. What would I look for for see if I have one and if it's plugged?
Yup, Our old P-30 with a 454 had the frame mounted tank filter.
Yeah, We've been driving it since last may. Put nearly 5K miles of her. She's a good coach. It's got an old style fuel cap, it's literally just twist on to keep fuel from spilling out on curves. No pressure or anything. It does sound like a shortage of fuel. Wondering if I have another fuel filter somewhere I don't know about.
Okay... Where would I look for this sneaky bastard... should I have one? I assume it would be between the fuel tank and the fuel pump... since the only filter I have found it after the pump and before the carb. That's the clear one in the pics above.
I went ahead and traced the fuel line from the pump to the tank. There is no other fuel filter. :( I was hoping it would be something that easy.
Fuel line goes back from the engine bay where the pump is mounted, on the passenger side. Down to the a cross beam just behind the propane tank and across to the fuel tank where it is attached to what is likely a fuel pickup?
I can access this under our couch via a cut out in the floor.
Also, It's late and we've got to put the kids to bed and I can't do much more in the dark anyhow, so I'll check back in in the morning. We'll probably try to drive it first thing and see if we can at least get it off of the hill.
Yes you do have a catalytic convertor. It looks like a muffler and they do plug up, usually can tell by no pressure coming out the tail pipe.
Good to know. Was just doing some research on these now that you gave me that tip. I can't really check anything else tonight... but I'll report back tomorrow and see if it's clogged.
If it is, can I just remove it temporarily until I get to the next town?
OK, first look down inside the carburetor and have someone pump the throttle. The two primary barrels have accelerator pump nozzles that should produce a strong stream of gasoline aimed at exactly a the crack where the throttle butterfly opens against the carb body. This should give good throttle response when you step on the gas.
If you don't get a good stream out of both pump nozzles, pull the hose/fitting where the fuel hose connects to the carb where your arrow is pointing in the first phono. Put the end into a Coke bottle and turn on the ignition. You should get a good flow of gasoline into the bottle WITHOUT the engine running. The carb only needs 5-8 psi of pressure.
That failing, check for voltage at the electric fuel pump to make sure it's working OK.
A bad or plugged Cat will usually idle OK but lose power as you add more load.
Sounds like fuel starvation to me. Usually a problem that occurs after a component has been replaced has something to do with the installation of the new component.
Do you have a second tank and a changeover switch?
Pierce
I am not an auto mechanic by trade but I did a little research but research to verify. Your pressure regulator that came with the model pump in your link comes preset to 14 psi. Some hot rod forums say you should run around 7-8 psi on the carbs. Anything too high can cause all kinds of strange symptoms. To adjust your regulator you loosen the lock nut and turn the adjustment screw counterclockwise to lower the pressure. But you need some sort of inline fuel gauge to adjust the pressure. Seems to me it is something to do with the fuel pump install that changed things. Just my thoughts after reading your posts. Hope you get it figured out and get back on the road.
Mark
Hey
@craneman - I went ahead and took pics of my exhaust setup. 0277 is from the engine down. 0278 is the middle of the exhaust pipe. Looks like this is where the pipes were extended to reach down the frame. 0276 is the rest of the exhaust pipe. This is mirrored on both sides of the coach. So there is two of everything and they match.
This pic didn't attach on the last post.
Make sure that the new fuel pump isnt sucking to much fuel and causing the hose to crimp under the pressure.. also I would assume a pressure regulator is needed with an electric fuel pump to properly set the pump pressure..
Loosen the gas cap sounds like the tank vent is blocked.
Good thing you are not in California, they would make you go back to single exhaust with a Catalytic converter. That eliminates that possibility for your problem. Hard to guess problems without actually being able to have the vehicle. The short list would be a broken baffle in the exhaust, fuel starvation or jumped timing chain. When you get the chance start the engine and see if the exhaust on both sides seem equal. A broken baffle in a muffler would cause heating and loss of power. Sorry I can't be of any more help. Keep posting what you are trying and the results.
Forget the baffle I just saw that you have glass packs. and they usually don't plug up.
The inlet gas filter in cranemans post 1is not visible. It can be inside the the carb body itself. Only access to this tiny filter is at the inlet fitting
@craneman - started the engine this morning. Cold, it starts up fine and idles well. Maybe even a little high.
Felt the exhaust on both sides. It feels like the passenger side may be putting out more pressure. Can't be sure though without a gauge.
If you changed the fuel pump to something different and that is the only thing changed it is safe to assume that is where the issue is.. To much pressure or not enough pressure.. how far from the gas tank is the new fuel pump? if its working good in the am I want to guess its pressure.. how cold is it? fuel lines might be hard if its cold. They get warm and soften up. Just thinking out loud.
How long has it run with this pump installed?
Go back and do what Pierce suggested . Take the air filter off and watch the fuel flow as it runs and dies. When it quits does it still have fuel when you pump the pedal? My guess is that it does not. If not pul the hose off and turn on the pump into a bottle. If it fillss the bottle but slows down after 10 secs the inlet plumbing is faulty, the filter is plugged etc.. Use a big enough catch can to run the pump 20 sec or more.
Look at the , Frame filter , tank screen , tank line missing/ bent , swollen. ETC. Tank not vented .
Good chance of the fuel tank hose blocked up . The pump makes a different sound when happy and flowing fuel, and when plugged up and not flowing fuel. If the pump fittings are loose it will also starve and quit.
Can you take the line off from the pump and blow back into the tank?
If the fuel pump is mounted near the tank and 10 ft or more away from the carb the fuel pressure should be OK. Carb pressure should be as stated, max about 7#.
The fule pressure regulator can shut off the fuel . If it fails the flow test, bypass it and retest.
The fuel filter, inlet lines, and regulator are the highest percentage of failure, in that order. MOL
If it flows lots of fuel while it quits , might be spark fault. Watch it run while monitoring spark . Pull a coil cable way from the post and crank it over listening/wacthing for spark .
If it passes both of these test. Get a heat infrared gun and check the exhaust system for cold spot. Both sides should be within 20 degrees of each other . and sound about the same at the outlets. Old Glasspacks can rust the innner screen apart and trap the glass , making a plug.
Check the wire to see if it has continuous power and doesnt cycle off for any reason. Overheating or something.
The fuel requirement is by far the highest when cold on choke . If it runs 10 min in the morning your fuel system is probable OK.
You could still have the filter partially plugged and the dirt falls down on shutoff.
Making Your Quadrajet Perform, Like it Should! (http://www.superchevy.com/how-to/engines-drivetrain/1610-making-your-quadrajet-perform-like-it-should/)
Go to this site and scrowell down to number 28. This is the filter that is probably plugged. Hope this works and restores your power.
Jason
Have some one raise the rpm and if you don't notice a big difference in the exhaust flow between sides go on to other possibilities. That pump from Summit has the external regulator, you might give them a call and see what the factory setting is. It will flow more than you need as far as volume. I doubt you have the tools to set the pressure on the regulator. It should have around 7 psi.
I see Jason has posted a picture of the filter I mentioned earlier.
With gassers, always better to have electric pump as close to the fuel tank as possible. Exact reason you stated - they "push" a lot better than they "suck". Many fuel pressure regulators used with high volume fuel pumps have a bypass feature that returns the excess fuel to the tank via a separate fuel line. This allows the fuel tank to act as a "heat sink" for the fuel, much the same as the fuel system in our diesel coaches.
You might have a thermostatically controlled flapper valve in one of the exhaust manifolds. On cold starts it is closed and sends the exhaust from that manifold under the intake manifold to warm it up quicker. Once engine warms and it opens, exhaust flow from both sides should equalize.
I would go back to a mechanical pump like the engine had originally and install a pressure gauge, and regulator if needed.
And if I use an electric fuel pump at all I wire in an automatic shut-off switch so in case of an accident fuel won't keep pumping.
The factory pumps were a little troublesome on the 454's That blue Holly pump will run a 598 cu. in. big block 9.42 @ 143 I am using it in my Camaro. Also a bad idea to run both as if the diaphragm fails in the mechanical it will fill the crankcase up with gas.
Yes, bypass and put a plate (most auto parts stores) on the block. No need for the mechanical pump.
If your diesel starts either not using any oil at all or seems to be higher on the dipstick, smell the dipstick for diesel. Lift pumps that bolt to the crankcase can also have partial failures with the diaphragm leaking and contaminating the oil.
Pierce
Checked this. It's not crimping fuel lines. The pump came with a regulator. Which is installed after the pump and set to the factory settings.
Just so you all know, I was able to turn it on and drive it the rest of the way up the grade today and get to our park. I won't be driving it again until tomorrow.
In the mean time, I found a neighbor camper who had carb experience and he looked at it with me. Suggested that the placement of the fuel line from the electric pump the PO installed was probably poorly chosen because it was right over the engine. We moved to the side where it should have more air flow around it and now be basically sitting in a hot box. Hopefully that helps.
We'll will be driving in to town tomorrow and I'll be able to check on some of the other things that are listed here.
@Protech Racing - Thanks for all of the tips. I'll try to go through all of those tests over the next couple of days.
@jerrett - Thanks for that article. I'm gonna go through that whole thing just for fun. But that fuel filter in the pic isn't like mine. I did pull off the fuel inlet line and look inside. There is no filter inside there. Did that with the neighbor guy. That was his first thought too. But no filter.
@craneman - I'll do the exhaust check and let you know. On the regulator, it's just adjusted with an allen wrench and came with instructions on how to do it, but a warning that I shouldn't have to. It doesn't say what it's set to. And the tool I don't have is something to check the pressure with.
If you are up and running now don't worry about the regulator. As Summit said it is set for normal use. Do see if you have the bronze or paper filter inside the boss on the carburetor. They didn't all come with them and if you don't have one don't worry as you have an external filter.
Normal use> Injection or Carb? I wiould think its 2 different settings I think my LS motor ran at 45psi or higher (been a while)
1986 big block Chevy Quadrejet carb.
@craneman - This is a different topic, but I was told today that switching out the Quadrajet for mechanical holley carb would do wonders for the engine. You know much about that?
The Holly is good for massive amounts of Fuel.. Horsepower... Quadrajet is good for stable running and fuel economy . My Holly woke my chevy 305 up but cost me a 1/4 tank to go accross town and back.. not so much with the quadrajet.. Less hp also.
454 quadrajet is OEM.. built for the motor..My holly was always an issue but I overcame it with an eddlebrock ... same as quadrajet
Been there done that. But for a lighter vehicle.
The small primaries on the Quadrajet are what give it good mileage. When you need, it the big secondary's have power. The Holly has almost the same primary as the secondary. More for racing. I personally would stick with the Quadrajet for your application. As far as the mechanical secondary's on the Holly they will open before you have enough rpm to need them. The beauty of the Quadrajets vacuum secondary's is it only opens when you can use them.
I would not use a Holley or a Quadrajet, Go with the Edelbrock Performer, just like a Quadrajet, but works much better.
A 650cfm instead of the larger 750cfm would give you more low end torque and much better mileage.
You won't be revving that engine to 6-7000 rpm to ever use the extra airflow the large carb has.
Check your spark plug wire order. If one of the wires got crossed during all the maintenance, this can result in your symptoms: overheating, lack of power, stalling, and flames shooting out of the carb while backfiring, etc...
Ask me how I know this. Had a 454 once upon a time.
Hopefully the jet(s) didn't get clogged during the maintenance.
Ignition timing needs to be checked. Timing chain could have jumped a tooth which will retard the timing causing a low power condition. Usually they jump when you shut down the engine. But can jump when running under the right conditions. How many mikes on engine ?
Quick update on this:
We drove 55 miles today. No issues. Temp stayed normal. I have more power than I did with the old fuel pump. Seems to need less throttle to hold highways speeds. Keeps finding myself speeding... which is a problem I've never had before.
O rly things I changed since the fuel pump and dieing on the side of the road... rerouted fuel line to not be directly over the engine. And wired the auxilarly electric radiator fans to a dashboard switch instead of the probe thermometer switch. I ran them for the whole drive.
I'm not sure if I've solved my issue... I feel like those two things were not difficult enough... I didn't injure myself doing them... and there was no cussing involved... so my problem can't possibly be fixed. Lol. I hate intermittent issues.
When we stop for a longer period of time next week, I'll run all the tests I haven't completed that you all have suggested and report back.
The Radiator fans if not connected correctly might have been drawing to many amps and causing issues with the power supply? Still guessing on this one but if its fixed for now.. I will hope you are past the issue.. ^.^d Good Job!!
http://truckroadservice.com/barth_attachments/vapor_lock_App7-7.pdf
Lol that looks like them old things we used to use as kids... A relic lol..
Chilton's (sp) at its best
Thanks @jcus! I actually already had that pdf. It's why I replaced the fuel pump in the first place. But I'm glad to see I'm not alone in thinking that was the issue.
Chilton's ^^^ recommends an electric pump to feed the mechanical one in certain instances.
UPDATE: So, I was able to drive the coach from Carlsbad NM to San Antonia TX. No longer had any problems with it dying or being fuel starved.
I did have my starter solenoid go out (simple napa replacement) and I have one of my spark plug wires that keeps getting burned up and then causing mis/back firing. I replaced that and wrapped it with spark plug wiring heat shielding. Hope that keeps that from happening again.
I'm hoping that's the end of my issues... though i'm still very surprised that I was able to fix the vapor lock issue with the fuel pump/line rerouting/and putting my aux fans on a switch.
But the coach is running better than ever.
Congrats! Don't be surprised - sometimes Karma cuts you a break. Enjoy the "easy" win...cuz they aren't all like that.
Thanks Chuck!
Glad you got your coach to go Alchemist without dying. I had an 89 Georgie Boy once with a ford gas engine. The engine sometimes would just stop for no apparent reason. I would be checking for the cause and after awhile it would start and run fine, until the next episode which might be a day, week, month later. Changed fuel pumps, insulated fuel lines, and finally figured it was vapor lock, but could not find the cause, because it would happen sometimes when it wasn't that hot and on some hot days would run fine. The air intake to the carburetor was routed to the right front side of the engine radiator where it would normally get fresh air, but under the right condition hot air off the radiator would recirculate into the intake and heat up the carb enough to cause vapor lock. I found this out by chance when I installed a longer air intake farther away from the radiator. Used a piece of metal clothes dryer exhaust hose. Never had a problem after that. There was about a 4" gap above the radiator and body of the RV that would let the hot air off the back side of the radiator recirculate and be pulled into the carb air intake. I think the direction the wind was blowing and speed of the vehicle may have had something to do with the problem.
Regarding your gas starvation problem, I may have missed this info in the foregoing but if no one mentioned it sometimes if your vent tube from the gas tank to the filler area has a sag/loop in it and if you over filled the gas tank, your vent tube can become clogged with gas acting like a P trap. This can create a vacuum situation in the gas tank preventing a good flow of fuel to the engine. The excess gas will eventually evaporate and allow the engine to run properly. Check the vent tube and make sure it"s angle will allow it will drain straight down into the tank.