Questions and Answers

Home Not So Sweet Home Q. Hi There Vincent! I am in a quandary as to what to do. I have asked several knowledgeable people and no one seems to have a clue. My 1983 454 MH ran like a champ, but this recently purchased 1989 just won’t rev. It is all stock including exhaust system, however I am contemplating going to a more free flowing tailpipes and mufflers system and a K&N Carburetor Air Breather filter.

The tailpipe portions are 2 1/4” O.D. / 2 1/8” I.D.. The exhaust pipes between the factory stainless steel (header-like) exhaust manifolds and the mufflers is very close to three inches in diameter, and has a factory installed heat shield affixed to them.

It has a twin Air Injection Pump system. (Where can I get a diagram of this system and of the Vacuum System???)

Back to the won’t rev part.

After selecting first gear manually to hold it in first when going from light to light a block at a time in heavy traffic so that it does not shift to early, I have observed a strange happening on several occasions. After getting the machine rolling I mash on down on the gas to kinda keep up with traffic.

(Here It Comes) Nearing the next signal and thusly while I am slowly raising my foot from the gas pedal it reaches a certain point and the engine comes alive. The RPMs noticeably raise and you can feel the improved acceleration. Shades of my old 1983 454. I do not think that it is fuel. Lordy O Lordy, it gets lots of fuel. I think that something is letting it get air somehow. What do you think???

The previous owner had a rebuilt Q-Jet installed on it to get it through Oregon DEQ and I had to take it to a Chevrolet dealer to get it leaned out before it would pass Washington DEQ. I am thinking of an Edelbrock 1906 replacement but????? I don't know anything. Please, Please Advise.

1989 Chevy / Class A Southwind Motorhome
Engine size 454
Automatic Transmission
51xxx
Carb Quadrajet
P/S, A/C, Cruise control

Thanks for your time.
Ed

A. It sounds like a loss of fuel to me when you describe that when lifting the gas pedal you hit a sweet spot. It may be "de-tuned" to get through emissions. A clogged fuel filter can cause this BUT with a carburetor you have a bowl full of fuel to start with. If it happens right off the line from a stop it's probably a carb/jet/metering problem. Even with a big block you should be able to get 50-100 yards on a bowl full of gas before a clogged fuel filter will slow you down. The filter should be fairly easy to check. It should be at the line inlet to the carb. BUT being a motorhome, you may have more than one filter in the system so check the lines all the way to the tank. As for air pumps, there should be a diagram under the hood for it or available from the manufacturer.

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