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Hello, first timer here. I'm about at the end of my rope here with my truck. It's an 87 S10 blazer with the 2.8 TBI. It has served me well for the last 6 years, with no issues up till the last year. About a year ago, I was cleaning it and decided to clean under the hood. I sprayed it down, degreased it, and so forth. Well since then the fuel pump prime circuit has never worked. I put up with it for the last year, thinking it's a computer issue.
In August, I'm driving it to school and twice in one day it stops running on me. I can restart it later, but I still decide to park it till I can work on it.
About a month ago, I start messing with it finally. It's a long story, I'll give you the quick version. I replaced the ignition module, coil, fuel pump, fuel pump relay, and checked all the wiring. The ground to the fuel tank was loose, but I resoldered that. I also replaced the computer with a reman... TWICE. The first one didn't help the prime issue. It also died on me up the street. The second replacement went up in smoke... literally. The 3rd computer (4th counting original, I bought this used because I suspected the PROM chip) is still kicking, but it doesn't prime still. So now I've got a running truck, but it doesn't prime still. I'm exactly where I was a year ago.
Here's what I'm looking at. There is a tan wire that goes to the fuel pump. That circuit is good, that's been verified. There are three ways of powering that wire. 1) a jumper wire under the hood 2) a relay, which is turned on by the computer (which is my main problem, it never turns on), and 3) the oil pressure switch (the only thing turning my fuel pump on, it starts once I get oil pressure). So basically, my main culprit is that my fuel pump relay isn't being turned on by the computer. I've checked that wire, it gets 12 volts when I check it w/o the relay attached, but what's weird is once the relay is plugged in the relay drops to under 1 volt. I've checked all the connections over and over.
I've been told to check the wiring, which makes perfect sense, but what boggles my mind is that my fuel pump prime DID work TWICE! Both times were with the reman computer, and the old PROM. The prime would work in both cases a couple starts after I hook the computer up, then I'd go to drive it the next day and it wouldn't prime anymore. I do get a code 54 when I crank for a while, I do know that it's for low fuel pump voltage (duh).
I HOPE someone on here has some kind of answer for me. I've been over the Mitchell wiring diagram several times, asked 3 mechanics, and even has a former GM engineer hook it up to a machine of his. I can't seem to catch a break with this. I really want to get this back the way it was, the engine itself is a recent GM crate engine. I would like to keep it with that engine, but if I can't get it fixed, I'll have to resort to a carbed 350 which I don't have the time, money, or motivation for right now.
Thanks in advance! Sorry for the novel, but this is the short version!
In August, I'm driving it to school and twice in one day it stops running on me. I can restart it later, but I still decide to park it till I can work on it.
About a month ago, I start messing with it finally. It's a long story, I'll give you the quick version. I replaced the ignition module, coil, fuel pump, fuel pump relay, and checked all the wiring. The ground to the fuel tank was loose, but I resoldered that. I also replaced the computer with a reman... TWICE. The first one didn't help the prime issue. It also died on me up the street. The second replacement went up in smoke... literally. The 3rd computer (4th counting original, I bought this used because I suspected the PROM chip) is still kicking, but it doesn't prime still. So now I've got a running truck, but it doesn't prime still. I'm exactly where I was a year ago.
Here's what I'm looking at. There is a tan wire that goes to the fuel pump. That circuit is good, that's been verified. There are three ways of powering that wire. 1) a jumper wire under the hood 2) a relay, which is turned on by the computer (which is my main problem, it never turns on), and 3) the oil pressure switch (the only thing turning my fuel pump on, it starts once I get oil pressure). So basically, my main culprit is that my fuel pump relay isn't being turned on by the computer. I've checked that wire, it gets 12 volts when I check it w/o the relay attached, but what's weird is once the relay is plugged in the relay drops to under 1 volt. I've checked all the connections over and over.
I've been told to check the wiring, which makes perfect sense, but what boggles my mind is that my fuel pump prime DID work TWICE! Both times were with the reman computer, and the old PROM. The prime would work in both cases a couple starts after I hook the computer up, then I'd go to drive it the next day and it wouldn't prime anymore. I do get a code 54 when I crank for a while, I do know that it's for low fuel pump voltage (duh).
I HOPE someone on here has some kind of answer for me. I've been over the Mitchell wiring diagram several times, asked 3 mechanics, and even has a former GM engineer hook it up to a machine of his. I can't seem to catch a break with this. I really want to get this back the way it was, the engine itself is a recent GM crate engine. I would like to keep it with that engine, but if I can't get it fixed, I'll have to resort to a carbed 350 which I don't have the time, money, or motivation for right now.
Thanks in advance! Sorry for the novel, but this is the short version!
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