80's 454 fuel supply challenges
Long time first time.
I have an 86 The Executive with a newish crate 454 and 95 Chev TBI on top of it. On a recent trip, we had some intermittent stalling except when I'd step on the gas at which point it would rage forward until I let off the gas. Strangely, that issue went away if we turned on the generator, and later, after refueling, we didn't have to run the generator and it was fine and we traveled another 100 miles home without incident, including a multi-hour traffic jam in the Utah mountains.
More recently, we went on a trip and made great time on the interstate, even passing some Uhaulers on hills. We refueled and as we pulled out, the ol thing stalled completely. I was able to restart and work the accelerator to keep it running but it would only just idle and maybe give me 1/16th the power if I lightly touched the gas. We turned around, spent the night, and hoped it was just a cool down issue. The engine always runs from 220 to 280 degrees.
No luck with that, so we limped over to a small town garage and started down the usual checklist. We replaced all fuel filters, checked fuel pressure and checked the timing. No luck with anything. We went to a second place that had a big block specialist and swapped out the ignition controller, idle air controller and even rebuilt the TBI (which strangely didn't have its gaskets after a previous rebuild), but no luck. We concluded it must be the fuel pump, but there were none available for days. I changed the fuel pump the next day, and still, no power.
Strangely, the plastic protective shroud around the pump wires had melted in a few places between the engine and the pump...
We cut bait and got a shuttle back home, then I drove back to it the next day after remembering I didn't hear any noises coming from the fuel tank selector when the key was turned, which I had heard during some previous repairs. I disconnected the fuel supply and return and put them in separate gas cans - one full, the other empty - to see if it would work. Sure enough, it started right up and ran pretty well, so I replaced the selector, but it still didn't work, so i just bought five bucks worth of plumbing parts and bipassed the selector, which looks like it has low pressure, high volume helper pumps. It ran great for another 120 miles in the hot Utah heat.
But! When we arrived at our destination, it stalled a little when I restarted the engine to move to a second location. When I checked in there, it sat for about 5-10 minutes. I hopped back in to restart it, and there was obviously no fuel getting to the engine. I coasted to our spot with the two pumps of brakes I had. I then replaced the fuel relay and was able to start it up and get into our spot.
The end of the next day, I fired it up and started to head out of town, thinking the fuel relay had been the culprit the whole time, which would have explained why the switcher wasn't working and pump might have been heating up wires to the point of melting the shrouds (wires were still in good shape). BUT! We got just a couple miles out of town when it started to slow down and lose power. NOT AGAIN! I almost changed the fuel pump back to the original, but thought the new relay might have been trying to send power to the tank selector, so I disconnected it, fired it up, and it seemed things were great.
UNTIL! We refueled again. I put premium in thinking it would help use maybe a bit less gas thus less strain on the pump. But, when I tried starting it again, it wouldn't start, and made some new weird noises like the starter wasn't releasing after I released the key. After a couple minutes, it would start and had power, so we were on the road again. All was well.
But it wasn't, we started losing power again, but it was like it was before, with maybe a high idle and no real power unless I floored it. We made it another 180 miles like that and got home. Strangely, it never went above 220 degrees that whole stretch, which included some steep mountains between Helper and Spanish Fork.
It stalled at a stop sign 200 yards from our house after idling downhill a couple blocks, but I restarted it and it seemed the power issue had fully reset, it didn't stall, sputter or fight back. But it was a very short distance.
My theory is the fuel relay was indeed bad, that the pump is struggling and drawing too much juice trying to feed the big engine and that power hasn't been getting back to the switcher for a while. But it's odd things work sometimes and not others.
WHAT IS HAPPENING???? HELP! Thanks
I have an 86 The Executive with a newish crate 454 and 95 Chev TBI on top of it. On a recent trip, we had some intermittent stalling except when I'd step on the gas at which point it would rage forward until I let off the gas. Strangely, that issue went away if we turned on the generator, and later, after refueling, we didn't have to run the generator and it was fine and we traveled another 100 miles home without incident, including a multi-hour traffic jam in the Utah mountains.
More recently, we went on a trip and made great time on the interstate, even passing some Uhaulers on hills. We refueled and as we pulled out, the ol thing stalled completely. I was able to restart and work the accelerator to keep it running but it would only just idle and maybe give me 1/16th the power if I lightly touched the gas. We turned around, spent the night, and hoped it was just a cool down issue. The engine always runs from 220 to 280 degrees.
No luck with that, so we limped over to a small town garage and started down the usual checklist. We replaced all fuel filters, checked fuel pressure and checked the timing. No luck with anything. We went to a second place that had a big block specialist and swapped out the ignition controller, idle air controller and even rebuilt the TBI (which strangely didn't have its gaskets after a previous rebuild), but no luck. We concluded it must be the fuel pump, but there were none available for days. I changed the fuel pump the next day, and still, no power.
Strangely, the plastic protective shroud around the pump wires had melted in a few places between the engine and the pump...
We cut bait and got a shuttle back home, then I drove back to it the next day after remembering I didn't hear any noises coming from the fuel tank selector when the key was turned, which I had heard during some previous repairs. I disconnected the fuel supply and return and put them in separate gas cans - one full, the other empty - to see if it would work. Sure enough, it started right up and ran pretty well, so I replaced the selector, but it still didn't work, so i just bought five bucks worth of plumbing parts and bipassed the selector, which looks like it has low pressure, high volume helper pumps. It ran great for another 120 miles in the hot Utah heat.
But! When we arrived at our destination, it stalled a little when I restarted the engine to move to a second location. When I checked in there, it sat for about 5-10 minutes. I hopped back in to restart it, and there was obviously no fuel getting to the engine. I coasted to our spot with the two pumps of brakes I had. I then replaced the fuel relay and was able to start it up and get into our spot.
The end of the next day, I fired it up and started to head out of town, thinking the fuel relay had been the culprit the whole time, which would have explained why the switcher wasn't working and pump might have been heating up wires to the point of melting the shrouds (wires were still in good shape). BUT! We got just a couple miles out of town when it started to slow down and lose power. NOT AGAIN! I almost changed the fuel pump back to the original, but thought the new relay might have been trying to send power to the tank selector, so I disconnected it, fired it up, and it seemed things were great.
UNTIL! We refueled again. I put premium in thinking it would help use maybe a bit less gas thus less strain on the pump. But, when I tried starting it again, it wouldn't start, and made some new weird noises like the starter wasn't releasing after I released the key. After a couple minutes, it would start and had power, so we were on the road again. All was well.
But it wasn't, we started losing power again, but it was like it was before, with maybe a high idle and no real power unless I floored it. We made it another 180 miles like that and got home. Strangely, it never went above 220 degrees that whole stretch, which included some steep mountains between Helper and Spanish Fork.
It stalled at a stop sign 200 yards from our house after idling downhill a couple blocks, but I restarted it and it seemed the power issue had fully reset, it didn't stall, sputter or fight back. But it was a very short distance.
My theory is the fuel relay was indeed bad, that the pump is struggling and drawing too much juice trying to feed the big engine and that power hasn't been getting back to the switcher for a while. But it's odd things work sometimes and not others.
WHAT IS HAPPENING???? HELP! Thanks
