About Van Expertise I have been maintaining a fleet of approximately 55 light, medium and heavy vehicles for over 20 years. Most are 4X4 pickups and off road fire fighting trucks. Some medium duty trucks. Some military light trucks.
I can answer most questions concerning 4X4 engine, drive line, suspension, electrical, and fuel, both diesel and gasoline. Ford, GM, and Dodge, old and new, but prefferably not newer than 99.
Expert: Van Date: 7/19/2007 Subject: 1993 Pontiac Transport
Question Hi Van, I have two questions. 1. My Transport backfires so badly it blows the exhaust system apart. The exhaust system WAS new so no bockage. A shop checked Ignition Module, MAF, IAC, MAF sensors, and computer and said all was fine. The problem is intermettent. Most parts have been replaced (fuel pump, filter, egr, etc.) Someone said that this may be an electrical problem and the shop said that an exhaust valve was stuck open and the engine had to be replaced. Now, I know that if an exhaust valve was stuck open that doesn't mean scrap the engine. They were also telling me this without even pulling the valve covers. The van is also picky about starting. Most times you can crank it and crank it and it will not start, but walk away for a bit and come back and it fires right up??!! This is a distributered 3.1, so no CPS. That was one of the things I had thought about. The backfireing has also been a problem that has sytematically gotten worse over a few months. Is this a short somewhere?
2. I have a 1988 Ford F250 4x4, 5.0L 302, 5 speed (m5r2). The problem is that I keep blowing out low pressure pumps in the rear tank. I'm on my fifth pump and I cannot figure out what is wrong. I have checked the wiring, and it's fine. I even replaced the pigtail going to the sending unit. The fuel system has been replaced entirely. Everything from the pump & sending unit, tank, lines, high pressure pump, filter, switch module, pressure regulator, everything!! This damn thing has a new fuel system, yet everytime I turn around I check the gauge and no pressure!! When I check the low pressure pump its inoperable. The engine has been a bit modified. 5.8 ltr throttle body, roller rockers, all accel electronics. Is the throttle body putting too much of a demand on the pump? I swear I'm about to rip it all out, and drop in a carberated 390cid. No more fuel injection! AARRGGG My third question is about the 390. What would you think would be the perfect drivetrain setup for a Ford 4x4 with a 390 dropped in it. Transmission?? Transfer case? I would like to stay with a manual transmission for off-road use. I am also looking for a dana 60 front for a 88 F250.
Answer Hi Ken,
Something is dumping raw gas into the exhaust for some reason.
A sticking valve, a ruptured diaphragm in the fuel pressure regulator, a bad injector, or a real dirty mass airflow sensor.
Are those fuel pumps actually shot? Have you tested one after removing it?
There are connections inside the tank, that while replacing the pump, you disconnect and reconnect, which might make a good clean contact for a while.
Can't help on the drivetrain. There are so many options, and the type of use you intend for it, and the performance you expect out of it, has too much to do with that decision. Good luck with it, though.
