m73m95

Hello again,

Ok, I'm still getting the random misfire, but no other codes.... Vacuum is steady (very steady) at 14hg. That's low, but its an old engine. IF it fluctuated, I would say it was a flat cam or something, but the gauge doesn't even wiggle.

When I drive it, it just feels like its not getting enough fuel. I'm trying to pinpoint this.

Do the fuel pumps get weak, or do they just go out?

Could it be a FPR? (would this send a code?)

any other ideas?

Thank you.... and sorry to be such a pest, I just want to get this truck fixed.

maxxman04

check fuel pressure. could be pump, filter, fpr. also, run compression test if you haven't already. inspect plugs. maybe have a shop check the cam offset (timing basically)

nauticstar87

Check your fuel pressure. that will help narrow it down.
EDIT: you beat me to it Maxxman.

m73m95

OK, I'm going to get a fuel pressure tester right now...


I did do a compression test. High was 170, low was 155.... pretty even.

maxxman04

the 155 is starting to push the limits. did you run a wet test on the low cylinder?

m73m95

OK, fuel pressure is rock steady at 55lbs.

I am completely stumped. The only code that shows up is "300" random misfire..... which I don't even think it has, cause it idles great and, in park anyway, it revs fine.

Only when driving does it not right. It has NO power. It will BARELY do 30mph. It feels like a fuel problem, cause it just falls on its face.

No MAF code, no MAP code, no O2 code..... anything that controls the fuel doesn't throw a code.

I dumped in 2 bottles of seafoam into the tank. tomorrow, I'll just go drive the **** out of it. It will either break for good, or....who knows....

Any other ideas?

maxxman04

do this. while vehicle is idling, pull the plug wires off of each plug, one at a time, and see which cylinder doesn't change rpm. then, have someone rev and hold engine at 1500-2000rpm, and do the same thing. if there is spark, engine will stumble and miss when plug wire is removed. if it doesn't change, then check the cap, plug, wire for that cylinder. also, check fuel pressure at 1500 rpm. 55 is at the lower threshold. put rig in gear, e brake on or someone holding the brake, check pressure. there should be no drop.

m73m95

ok, thank you.

I'll do that 1st thing in the AM.

silverado13

try replacing your fuel filter too