Fuel problem 92 Dodge 318 MPFI
Please give me some advice (or sympathy?).
I have a 1992 Dodge Ram 250 Full size conversion van with a nice 318 MPFI motor. Ive owned the van for three years. Ever since I bought it I have been plauged by an intermittent but frequent problem. Reading the fourm it sounds like I may not be alone.
The van sometimes refuses to start. More often when warm than when cold but it has happened cold too. Usually, almost always, if I hit it with starting fluid it will start but sometimes it will stumble and stall even after that. 99.99% of the time if I futz with it, eventually it will start.
One garage has replaced the fuel pump, the fuel pump relay, and all of the filters. All electrical connections have been checked and found to be good. On once occasion, the machine failed to deliver spark which also prompted us to replace the coil. Out of the van, the coil did test bad.
Giving up on that mechanic, I went to another mechanic. He did a tune-up which the van did need but obviously that was not the ultimate cause of the problem (we agreed on this before the tune up - but the job was over-due so we did it). At about the same time, I changed the ignition switch because it was occasionally not engaging the starter but again, we knew this was not the ultimate cause of the problem. I left the van with the mechanic and permitted him to take the van on parts runs and drive it on errands, lunch runs and the like for a couple of days. I was confident in this amount of time, the van would act-up and they could "catch it" while it was acting up. I got it back from them, with no charge and many compliments about how responsive and powerful the van is but, no problem found. As soon as I got it home, it acted up. Towed it back down there while the engine was still warm and it started right up. By now, we had agreed that I've tossed enough parts at the machine that we would not toss in any more parts until we found the cause of the problem.
Talking with a couple of amature mechanics, they suggested the Fuel Pressure Sensor may be defective. The mechanic disagreed, saying they tested it and it tested fine. Still, I stuck sixty bucks into this part the size of a bottle cap and tried it. The mechanic was right. I still have the problem and if anything it is worse.
I think I know that whatever it is that is causing this is something that is causing all of the injectors to not fire. The pressure is there and it is correct. I just don't know what it is that may cause this!
One final bit of information that you may find useful. Sometimes when I spray it with starting fluid it will run rough for a bit before it somooths out and runs like new. I'd guess that this happens about 25% of the time when I use starting fluid but only about 5 or 10% of the time when I don't (which is most often).
Any ideas appreciated.