'87 5.7 TBI issue
 

Hi,
First post, glad to be here!

I bought an older Winnebago class C motorhome (like a van cab with a camper on the back, going over the top of the cab).

It's an early TBI Vortec motor. I drove it 20 miles home, and need to fix a bad issue.

The engine runs great at idle, but if I give it more than just a LITTLE gas taking off from a light, it spits and sputters and misses - has very little power. I have to back off the throttle to JUST off idle to get the thing to move.

I know it's an old engine and lots of things need to be serviced, but where is a good place to start to tackle this HUGE issue? The engine looks stock, smog equipment and air cleaner are stock.

Thanks.

EDIT: I have checked the vacuum hoses and plug wires... Also, the engine sat for 2 years. The gas tank was near empty and it has fresh gas run through for 20 miles now.

I would start with the fuel filter, it sounds like it isn't getting fuel when you open up the butterfly valve.

Good idle with an acceleration flutter speaks to vacuum leak. Double-check that all those vacuum hoses didn't dry-rot during the two-year hiatus. Check the distributor parts for wear and tear, paying particular attention to the vacuum advance.

If that checks out, a compression check is probably in order. People usually don't go along driving something , then suddenly STOP driving it for no good reason. Many vehicles which have sat for long periods had a problem BEFORE they were abandoned for more dependable transportation, and it's usually something time sitting in a backyard somewhere isn't going to fix.

All I'm saying is you may have two sets of problems demanding your attention, the dormant motor dilemma(which you know about), and the REASON it became a dormant motor (which you don't).

Have you pulled off the distibutor cap? My 90 burban was playing a simular game and I found that it had accumulated deposits on the rotor contacts. Took a pocket knife to it and all was good.

Question. does it only do it under load?

Great suggestions, guys. Thanks.

I'll go back through the vacuum hoses and pull the distributor cap tonight. Once I locate the fuel filter I'll replace it. I'm assuming that it's on the right of the chassis by the tank, but I'll track it down.

I would like to pull the TBI unit too, I'm sure a rebuild kit and a good cleaning is in order. I think the rebuild kit comes with a new fuel pressure regulator diaphragm too.

Awesome site, thanks for the help so far!!!

Are there any simple mods that can be made while I'm 'in there' - Like air cleaner, EGR, AIR or any of the other systems that apparently came out around this time?

I love how rudimentary the cab is, the engine computer is just hanging out right behind the driver seat... The TBI is two simple injectors above an otherwise standard manifold.

I'm used to the Harley's 103CI FI or the 300C's HEMI setup. There are so many sub systems there. It's hard just to follow those systems. This is so 'back to basics' in some ways. Why do things have to get so 'system intensive' these days??? I guess it's the fear of global warming and all. Bring back the carb!!!!

There are a few things that you can do. High flow air filter, plugs and wires, throttle body spacer, coil,. The list can go on. Depends on how extreme you want to go.

Looks like there are some extra horses to be found cheap with this engine.

Thanks for all your help, guys. What a great site!!!

Thanks for the link, Gary. I do believe I'll be doin' a little modifyin' on the Scout's power plant.

TBIchips.com is a great site, even if you don't buy anything he has a lot of "how to" information for free.