Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #25 – March 22, 2018, 11:56:10 pm This pic didn't attach on the last post. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #26 – March 23, 2018, 12:08:54 am 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.. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #27 – March 23, 2018, 01:22:14 am Loosen the gas cap sounds like the tank vent is blocked. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #28 – March 23, 2018, 01:26:19 am 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. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #29 – March 23, 2018, 01:55:32 am 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 Quote Selected 1 Likes
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #30 – March 23, 2018, 09:30:24 am @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. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #31 – March 23, 2018, 10:02:48 am 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. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #32 – March 23, 2018, 10:08:25 am 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. MOLIf 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. Quote Selected 1 Likes
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #33 – March 23, 2018, 10:10:38 am Check the wire to see if it has continuous power and doesnt cycle off for any reason. Overheating or something. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #34 – March 23, 2018, 10:13:10 am 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. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #35 – March 23, 2018, 10:33:01 am 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 Quote Selected 2 Likes
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #36 – March 23, 2018, 10:36:46 am Quote from: AKATheAlchemist – March 23, 2018, 09:30:24 am@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.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. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #37 – March 23, 2018, 10:42:58 am Quote from: Ralph – March 23, 2018, 10:11:40 amI believe however, moving the electric pump was the main factor....no pump, mechanical or electric is going to pump vaporized/boiling fuel, but an electric might "push" the fuel on through was my thought.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. Quote Selected 1 Likes
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #38 – March 23, 2018, 10:55:10 am Quote from: AKATheAlchemist – March 23, 2018, 09:30:24 amCold, 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.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. Quote Selected 1 Likes
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #39 – March 23, 2018, 11:03:22 am 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. Quote Selected 1 Likes
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #40 – March 23, 2018, 11:15:42 am 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. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #41 – March 23, 2018, 12:06:39 pm 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 Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #42 – March 23, 2018, 01:14:36 pm Quote from: DavidS – March 23, 2018, 12:08:54 amMake 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..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. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #43 – March 23, 2018, 01:24:28 pm 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. Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #44 – March 23, 2018, 01:30:50 pm 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. Quote Selected 1 Likes
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #45 – March 23, 2018, 02:10:46 pm Quote from: craneman – March 23, 2018, 01:30:50 pmIf 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) Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #46 – March 23, 2018, 08:45:03 pm 1986 big block Chevy Quadrejet carb. Quote Selected 1 Likes
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #47 – March 23, 2018, 10:44:19 pm @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? Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #48 – March 23, 2018, 10:54:39 pm 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 Quote Selected
Re: Dead On Side Of Road: Fuel Starved/Vapor Lock? Reply #49 – March 24, 2018, 12:35:45 am Quote from: AKATheAlchemist – March 23, 2018, 10:44:19 pm@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?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. Quote Selected 1 Likes
Topic: Dead On Side Of Road: Fuel Starved/Vapor Lock?