I have a 91 GMC pickup with a 350 engine, with throttle body fuel injector. The truck is basically in good condition and engine runs, but only in good weather. I cant figure this one out at all. In the summer when the weather is warm and sunny, the truck runs like a champ. The minute the weather gets cool, the truck runs like total crap. It stalls, kills, runs rough, lacks power, and does all sorts of things except runs properly. Sometimes it will run good for a while, then seems to go into a state of chaos, then will run good again minutes or an hour later.
I've checked out numerous things, changed the plugs, fuel filter, air filter, made sure all vacuum hoses are ok, and all wires are plugged in tightly. Everytime I get it running right, (or seems to be), the next time i drive it, it's likely to begin running terrible again. Of course, if the weather is in the 60s or above and sunny, it runs perfectly every time.
I took it to a mechanic. He carefully looked it over and said everything looks to be working properly, but said there's no way to know for sure until it's connected to a computer, and said taht since my problem is intermittant, it may not show up on the computer at the time of the test. He told me it would cost me $200 to $300 to hook it to the computer. This does NOT include the cost of repairs or parts.
Well, I'm not going to stick $300 into just a damn test, then possibly pay hundreds more, when I only paid $1000 for the truck in the first place. I have fixed all my own cars since the 1960's and done so with basic tools and a few testers like a timing light, dwell meter, and electrical meter.
What really gets me, is that I have a 1989 Chevy car with a 307 engine and a carburetor. The car gets almost twice the gas milage, and it's nearly the same weight (empty) as the truck. It's not the extra 43 cu inches, it's those damn injectors causing the extreme over use of gas. (and thats when it runs good).
Before I even think of spending $300 just to test the damn thing, I'd rather replace the throttle body with a carburetor. I have an old 350 engine with a carb, so that wont cost a cent. I assume I'll have to change the intake manifold to make it fit. (of course I got that too on the other engine). Then I know the in-tank fuel pump needs to go, and be replaced by an electric fuel pump on the firewall. (I have that too). I wont miss that damn in the tank fuel pump either, after having had to replace the pump once, then replace the sending unit which sprung a leak. (no more tank removal sounds great).
My reason to post this is to find out about the ignition system. I heard that I need to modify the coil and other ignition parts, but what parts and how? Does anyone know?
What I want to do is turn this into a basic, simple engine, without all the junk added, and particularly without that damn fuel injection. I'll never buy another F.I. vehicle. Where I live, we do not have emissions testing, so I dont have to keep it stock.
Has anyone done any of this? What else do I need to know?
Thanks
Ralph