off-topic - need help with '85 Chevy RV problems

[Randall K.]

Hoping that some of you C-4 experts might be able to help. I have a 1985 RV, built on a Chevy P30 van chassis. Has a 454 coupled to a TH400, Qjet 7080212.

It recently has started to bog down VERY badly - and quickly - when in drive - won't go over 15 mph without dying or losing power. Idles OK, and will sustain high RPMs while in park.

Fuel filter OK - changed plug wires last year when it was running rough but would still sustain highway speeds. Within last year, new ignition module and new coil as well.

Any/all suggestions greatly appreciated!

Randy

[Clem Z.]

Re: off-topic - need help with '85 Chevy RV problems

[quote=Randall Krohn (43621);396724]Hoping that some of you C-4 experts might be able to help. I have a 1985 RV, built on a Chevy P30 van chassis. Has a 454 coupled to a TH400, Qjet 7080212.

It recently has started to bog down VERY badly - and quickly - when in drive - won't go over 15 mph without dying or losing power. Idles OK, and will sustain high RPMs while in park.

Fuel filter OK - changed plug wires last year when it was running rough but would still sustain highway speeds. Within last year, new ignition module and new coil as well.

Any/all suggestions greatly appreciated!

Randy disconnect the cat converter and take it fort a ride i will bet the converter is plugged

[Charles M.]

Re: off-topic - need help with '85 Chevy RV problems

Randy, I had the same problem years ago with an 89 Southwind. Turned out it had a second fuel filter along inside frame rail that was plugged. I got a good deal on the MH because owners could not find the problem.
Chuck M.

[Clem Z.]

Re: off-topic - need help with '85 Chevy RV problems

also check the exhaust pipe from the manifold to the muffler/converter. if this is a double wall pipe the inner pipe could also have collapsed and shutting off the exhaust flow same as a plugged cat converter.

[Joel T.]

Re: off-topic - need help with '85 Chevy RV problems

Randy;

Ditto Clem's comment on the catalytic converter. check to see if you get raw gas collecting on the top of the carb, that's another sign of clogged exhaust. I had this problem, believe it or not, with a 1975 Pinto (of all things) actually stranded me in the middle of nowhere, USA. A well placed hole punched in the engine pipe got me home.

Good luck,

Joel

[Clem Z.]

Re: off-topic - need help with '85 Chevy RV problems

I'm pretty sure 1985 G / P 30's are over 8550 GVW, and therefore don't have cat converters.......

I worked on a 87 GP30 with a 5.7 and TH400 a few years ago. (replaced the engine). I distinctly remember a 12ga tan wire coming from the engine / trans harness, and running along the RH frame rail to the tank. It was too big to be the fuel gauge sender, and I recall coming to the conclusion that it was for an in-tank electric pump..... The engine had a mechanical pump as well.

I could be all wrong, of course, but I very distinctly remember these being my conclusions. Just not how I came to them....

If it has an in-tank pump that has failed, the symptoms you describe would be logical.

the fuel pressure is a easy check just "T" a fuel pressure gauge into the fuel line at the carb and see what you have.

[Randall K.]

Re: off-topic - need help with '85 Chevy RV problems

Hi all

Dave -you are correct - there is no cat converter.

I didn't see any gas collecting on top of the carb while I had it idling - and high RPMs - in park.

Otherwise, all great suggestions. I too suspect that I may have an unidentified fuel pump at this point.

Unfortunately, here in St. Louis, our early spring will be coming to an end today, so I'll get to crawl underneath in the cold and damp by the time I get to it again.

Thanks!

Randy

[Clem Z.]

Re: off-topic - need help with '85 Chevy RV problems

you can check for collapsed head pipe by having some one stand at the tail pipe and feel if there is a good exhaust flow when you rev up the engine in neutral

[Joe L.]

Re: off-topic - need help with '85 Chevy RV problems

OK, I have another idea. The engine fuel pump has failed from the Ethenol in todays pump gas. If it's old enough, it won't have viton parts in it, and they swell up, and don't pump very well.

I've been changing a lot of fuel pumps on boats the last year or so..... I've taken some apart, and the rubber is all distorted and swelled-up.......

Dave-----


This is exactly the reason that I've been telling folks for quite awhile not to part with Big $$$$ for old NOS fuel pumps, especially the crimped style, in order to "squeeze out" that last judging point. Fuel formulations have changed a lot since these pumps were manufactured and these pumps could have a very short life in "today's world".

[Clem Z.]

Re: off-topic - need help with '85 Chevy RV problems

Not too sure about the use of the words "just" and "easy" in the above sentence with regards to this check in a GP30 with a 454, Clem. Sometimes it takes an hour to 'just' get the engine box off, if you have to remove the pass seat for clearance. (Very common in MoHos, they have big, over-sized seats). Then, how do you "T into the [metal] line"? I would suggest this:

Take the metal line off at the fuel pump. (Ever tried changing the fuel pump in a G30? Didn't think so. Not a lot of room to swing wrenches down there). Shouldn't have too much trouble taking the line off at the carb, as long as it isn't all butchered up from previous "mechanics" working on it.

Then go to the parts house and get (2) 3/8 hose X 3/8 inverted flare fittings, and a 3' piece of 3/8 fuel hose. You'll also need the "T" and fitting(s) as appropriate for your pressure gauge. Or a gage, if you don't have one. Set this all up and install it in place of the metal line for the test.

You can drive it with the engine cover off. It'll be nice and warm (and noisy). When you have the results, you can put the metal line back on, (I'd wait until it cools off, so you don't have a fuel fire), check for leaks, and put the engine cover back on.

Shouldn't take more than 3-4 hours, including the run to the parts-store. A little more than "just", I would say.

i have worked on a few MH and the fuel pressure gage i used connected between the fuel line and the carb inlet with a adapter. did you ever take a MH for a ride after dark with the dog house off,the exhaust manifolds get so hot they are transparent as you can see the exhaust port in the heads thru the manifolds. that is why so many cracked and they later used a stainless steel bellows in the manifolds to allow for expandsion