Okay,
So in the process of diagnosing the air compressor for the tag axle, we discovered the problem with the compressor is that the little power cable running from the dash back to the air compressor isn't supplying power to close the solenoid so that the compressor can draw the big power.
Anyways, this relates to a separate problem we were diagnosing. The headlights won't turn on.
They did when we bought the coach, but then while driving they suddenly lost power and wouldn't turn back on.
So, today we tested the headlight switch. It's good. Tested the headlights with external power supply. They are all four good. tested at least one relay that we thing is after the switch and goes to the headlights. That works.
The problem is that the little red power cable running to the switch isn't supplying voltage... same as the small power cable to the compressor solenoid.
Both of these items, the compressor solenoid and the headlight switch should be getting power when the ignitions switch is "on", possibly "accessory position, but it's not.
So my question, is does anybody know what might be wrong? Relay we cant find? Ignition switch partially bad?
Thoughts? Or dash wiring diagrams would be useful.
The headlights should come on even with ignition off. So it sounds like the main 12V power to the dash is intermittent. Does the coach start and run, or is the ignition completely dead at this point? There should be a main ignition relay somewhere under the dash with a fairly large wire connected to it and several smaller wires. When you turn the key this connects power to the dash. If you can find that, is there voltage getting that far?
That coach is built on the chev chassis so should have a main feed wire from the stgarter if I remember correctly and it should have a fusible link in this wire someplace. It sounds like the fusible link has burned through. You need to find a wiring diagram for a p30 chev chassis. If I was home I have one, but am in KY now.
My dash wiring has 30 years of people thinking they know how to wire a dash better than Foretravel, so, I can't help much with the schematic, but my dash has one fuse block for the switched accessories that turn on and off with the key, and one fuse block that's always on. If you have that, it could be that is not getting power.
If you have the same headlight switch I do, the knob you pull out to turn on, I had one like that on my old 69 bronco. It would work fine at home, but when driving it would heat up and shut off, typically on a unlit winding mountain road. That certainly added a little excitement to the eventing.
UPDATE.
This was a pain in the ass to figure out. The ignition switch was having intermittent power issues. Sometimes it would be perfect. Sometimes it wouldn't. Sometimes is would start quick. Sometimes it would take a few minutes to start. Then, I took it to get smogged (failed for running to rich) and it died on the side of the road... no power anymore. No longer intermittent.
Had several people tell me it was the ignition switch going bad on me. I took it off. Tested it. It seemed good to me. But I replaced it anyways. Also replaced the Neutral safety switch while I was under there... cause it was part of the same circuit. Still no power to the ignition switch.
But If I ran a wire from a hot wire in the dash to the back side of the ignition switch power wire... coach started and ran fine. So I knew most of the pieces in my starting circuit were good. Just the wire to the Ignition switch was bad somewhere.
So I started tracing it with a continuity meter. What a pain in the ass. had to take the whole dash apart to do that. Remove radio. Remove instrument cluster. Found the wire going into the engine bay... then promptly lost it and couldn't find in anymore.
So I went to Harbor Freight and picked up a wire tracer... found my wire again and traced it all through the engine until I found the break. The tracer made quick work of it. Should have started with that... would have saved me two days of headaches and work.
Anyways, there was a fusible link by the starter solenoid that was bad. It test good with continuity meter. But not with the tracer. Tracers dected the break. And when I touched the wire... it shattered into several small bits... so it was really bad then. Lol.
I had already purchased fusible links in various sizes when I was picking up the new ignition switch on a gut feeling. And turns out I was right.
Replaced it. All my power issues are resolved. Starts up immediately. Idles better. Much nicer running coach.
Now I've just got to find a mechanic who know how to adjust a carburetor for smog readiness.
Oh... and the headlights were a blown fuse. That was an easy fix.
You can only adjust the idle circuit of the carburetor. That will not solve the rich condition on the smog fail. The Quadrajet has know issues of plugs leaking in the bottom of the bowl. You need to take the carb to a rebuilder that knows Quadrajets, a carb kit alone might not help.
That's good to know. I was having a hard time evening finding someone who knew how to adjust the carburetor and also had room for an RV.
So, If I'm understanding you correctly... I can take the carburetor off and take it to someone who knows how to rebuild them?
Correct, but make sure they know the carb.
Awesome... just called Super Carburetors & Fuel out here in riverside. (Super Carburetors & Fuel Injection - Auto Repair - 2622 Main St, Riverside,... (https://www.yelp.com/biz/super-carburetors-and-fuel-injection-riverside))
They said they both knew the carburetor and how to rebuild it. Only $185 to do the rebuild. So we shall see.
Old technology is getting harder and harder to repair (with someone that understands it). New technology is pushing the old out and not many older techs still around (like they used to be)
Look into Affordable Fuel Injection up in detroit. They may sell a CARB compliant system for your engine that will improve drivability, economy, power, engine life and of course emissions. A buddy of mine just had them install EFI on a 1960s mustang with a totally destroyed fuel system (decades old gas) and it runs as good as a modern engine now. For the price (1200ish) it was a total transformation. I used their fuel injection on a ford 4.9 a few years back and it was flawless. They are a small company and their support is amazing. If your (super reasonable) carb repair doesnt work, I would strongly look into EFI before sinking a ton of money into chasing carb issues.
Their system uses a mercury ECU and all common off the shelf parts available anywhere, is OBD2 diagnostic capable, so it can be troubleshot and repaired anywhere at minimal expense.
X2 on this idea. Conversion to fuel injection would seem especially desirable on a gasser RV, since that type vehicle is more likely to see operation at a variety of elevations. Carbureted engines (naturally aspirated) are generally not happy at high altitude.
In a previous life, I owned a much-abused hotrod Skylark with a mid-70's big block Buick 455. One of the (many) previous owners had blessed it with a QuadraJet that featured a "altitude compensating" device. I could never find anybody who wanted to try tuning it, and it was
definitely above my pay grade, so I trashed it and installed a 750 Holley double pumper. After that it always ran great - Holleys I could understand! 8)
For the curious, here is a link to discussion of the ACQJ on the GMC motorhome forum:
[GMCnet] Altitude Compensating Quadrajet For Sale (http://list.gmcnet.org/pipermail/gmclist_list.gmcnet.org/2009-August/033982.html)
155-5515_IMG_2 - (http://www.gmcmhphotos.com/photos/altitude-compensating-q-jet/p22759-155-5515-img-2.html)
The Holley 3310 was the go-to back then.
The options needed for his 454 at Affordable Fuel Injection take the price to $1,500.00
The Q-Jet can be rebuilt to pass Cal emissions.
You can get a rebuilt Rochester for not much more than the rebuild price. Be sure to check that the choke is opening all the way if a rich mix is your problem.
I'm redoing a 1986 Grand Villa 33' also, with I guess a 1985 0r 1986 Chevy 454. I'm getting the carb. and distributor rebuilt now.
Hoping that changing the timing will help the gas milage a little.
Wantabe
I thought those had the mixture screws on them? or they could be drilled to reveal? or not? I dont remember off the top of my head
Those were air idle screws some had plugs blocking them off that could be removed. They will not alter the running mixture only jet changes do that.
As I recall, the QuadraJet used screw-in primary jets and fixed secondary fuel orifices, plus 4 moveable "metering rods". Q-Jet tuning was as much art as science, and required selecting the exact proper combination of primary jets, primary and secondary metering rods, metering rod hangers, and air valve spring tension from about a zillion different possible combinations.
It was rumored that divining the correct set of tuning components involved communion with the Dark Side, and possibly a blood sacrifice. :o
The Quadrajet has tiny primaries and huge secondaries. This is called a "spread bore" carburetor. As a direct result it will have better fuel efficiency than a "square bore" carburetor like most of the Holley performance carburetors. There actually are Holley spread bore carburetors available. Also the Quadrajet has a spring loaded air valve over its huge secondaries, which prevents overcarburetion at low rpm. This should improve fuel efficiency and low rpm performance, especially for a carburetor with tiny primaries and huge secondaries. I think most of the Holley spread bores have vacuum secondaries instead of a spring loaded air valve. I'm not sure if that works as well as a spring loaded air valve for your application. Holley carburetors have a long history of fuel leaks because they had (still have?) gaskets below fuel level. They were sometimes difficult to adjust, but if you got them adjusted perfectly they would make a race car slightly faster than other carburetors. This information is 20 years old so maybe it's inaccurate now. When I built the engine in my Chevrolet I chose a square bore Carter AFB and it's been trouble free and an excellent performer. It's not fuel efficient though. If it were my coach I'd consider an aftermarket rebuilt Quadrajet or a high performance aftermarket clone of the Qjet if the price was nearly the same as a rebuild. I wouldn't change to a square bore carburetor because the fuel efficiency will be even worse than it already is. It's likely the emissions would be even worse too. I'm writing this from memory so you should verify that this information is still accurate.
Is your air filter clean? Is your motor oil clean? Yes, that really does make a difference. It surprised me too! Are you sure the engine is running on all cylinders? Change your plugs, wires, cap, rotor, or anything else that is preventing the engine from running on all cylinders. Some of the newer engines don't have a distributor and that would eliminate the cap and rotor. Carefully remove the spark plugs and compare each plug's electrode to the photos on a spark plug color chart. Keep track of which cylinder each spark plug came from. You can learn a lot about what's going on inside each cylinder from the spark plugs. There are other things that affect emissions. Ask your mechanic(s) for suggestions.
I have worked on a few carbs in my time.
Carburetors? anyone?
Yup, still have my carburetor jet drill bit set.
Free up the exhaust? Go one jet size larger.
I had a Holly on my 76 Camaro ... Ran great and sucked the fuel... after the thing vibrated apart and I got tired of the leaks I bought a brand new Edelbrock 200 or 220 cfm If I remember... Ran almost as good as the holly with better fuel economy which didnt bother me as I was making 5$ per hour.. I could really tear up the tires with the holly..
Little off subject but back on it
Fuel injection was the next best thing since sliced bread.. Reliable, reliable .. did I mention reliable? and efficient
My parents had a 87 Grand Villa on a Chevy P30 with a 454 engine. It was great coach except it had a noisy valve lifter so we ran Marvel Myserty Oil in the fuel and the engine ran like a top. Steve
Carbs are not horrible just don't get carried away trying to reinvent the whole physics of fuel and air. Hot rod magazine did a comparison of several bolt on fuel injection systems ( they were all throttle body systems). They found no noticeable improvement to fuel mileage and performance over the professionally adjusted stock carb. The real big note was the improved cold to hot performance and the ease of set up. Fuel supply is an issue. You can install a pump at the tank and run new lines for the pressure or they sell a small tank you install near the engine that the mechanical stock pump fills and it pumps from that to the throttle body ( fuel gets hot and if there is a leak or an accident it could spill on something hot.
Carb rebuild is a cheap experiment, if it doesn't work fuel injection will cost you but it's nice to start up and drive away without waiting for the choke.
The Holley is very simple but is not good on fuel. The Quad will run leaner but has a lot more failure points.
The Aftermarket EFI can run closed loop , shut the fuel off on overrun ,etc. Hot start better . Just generally run like a modern car.
The carb can work as good as it did as new, for 200$ give it a try.
I struggled with Holley carbs for years and have a box full of them in the basement.
The best solution I found was the Edelbrock performer carbs. I never had to mess with any I installed after installation.
I figure you have a 454 engine in your coach, a spread bore Edelbock should bolt on.
Don't waste your time and money on a rebuilt carb.
Those performer carbs are nothing but a relabeled Carter AFB