92 454SS Hard Start stalls fuel pump runs continuously

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someotherguy

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We would run liquid filled oil pressure gauges on shovelhead Harleys - direct into the case by the rear lifter block, or up top off a fitting on side of the rocker box. The liquid would steady the needle but in the end the extreme vibration from the v-twin was murder on the gauge.

Richard
 

92Red454SS

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The few second prime is normal. I may have mis-read but I don't see the diagnostic step of what the pump does if you turn the key on (not start) and see how long the pump runs with the oil pressure switch disconnected?


It still runs 20 seconds with the oil pressure switch disconnected.
 

DerekTheGreat

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For poop and laughter, try and disconnect the tan & black ESC wire behind that plastic cover on the passenger side firewall. Try and restart the truck. If it runs just dandy, replace the entire distributor or ICM. Since yours only has 42k on it I'd just try replacing the ICM.

I've had the ICM fail in ways which if the engine tries to idle <1000rpm's then it just dies and falls on it's face. My '89 K1500 did this and just recently, my wife's '92 C1500. I could crank and crank & sometimes either truck would start & run but they both stalled when trying to approach hot curb idle. When I unplugged that wire in both cases, I was able to get the vehicles back home where I could work on them as that puts them in bypass mode.

Also, please post pics of your '92. :D I've seen lots of '90's, but none of the later years with the factory tach & overdrive transmission.
 

someotherguy

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What is the tan & black ESC wire.
It's the bypass wire for the timing advance - you disconnect it to set the base timing, which I *think* is 4 degrees BTDC on the 7.4? On the 5.7 it's zero.

Here's a write-up I did with locations for the wire; yours is likely in the harness bundle on the passenger side of the firewall in the engine bay, under the relay/junction block electrical convenience center cover that Derek mentioned.

https://www.chevytalk.org/fusionbb/showtopic.php?tid/269357

Richard
 

Schurkey

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IIRC - the liquid filled gauge will be inaccurate with the heat generated by the engine but, again my CRS (Can't Remember ****) syndrome is kicking in, lol
The dirty little secret about liquid-filled gauges is that YOU'RE SUPPOSED TO REMOVE THE RUBBER PLUG BEFORE CHECKING PRESSURE. When you're done, you put the rubber plug back in. Nobody seems to know this, and the folks that sell liquid-filled gauges aren't good about telling you how they're supposed to work.

In stationary service--I have a pair of them on my household water supply, one before the pressure regulator and one after--you'd mount the gauge so that the rubber plug is "straight up", and then poke a tiny hole in the plug. When the gauge is sealed, the internal gauge pressure (which changes with changes in temperature) distorts the reading. The gauge has to be un-sealed to read accurately.

You can't do this on a vehicle, because the vibration will cause the fluid to leak out. So you're reduced to popping the rubber cover off every time you want to check pressure, or you drain the damned fluid out permanently, and then press the rubber plug back in.
 

92Red454SS

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For poop and laughter, try and disconnect the tan & black ESC wire behind that plastic cover on the passenger side firewall. Try and restart the truck. If it runs just dandy, replace the entire distributor or ICM. Since yours only has 42k on it I'd just try replacing the ICM.

I've had the ICM fail in ways which if the engine tries to idle <1000rpm's then it just dies and falls on it's face. My '89 K1500 did this and just recently, my wife's '92 C1500. I could crank and crank & sometimes either truck would start & run but they both stalled when trying to approach hot curb idle. When I unplugged that wire in both cases, I was able to get the vehicles back home where I could work on them as that puts them in bypass mode.

Also, please post pics of your '92. :D I've seen lots of '90's, but none of the later years with the factory tach & overdrive transmission.
I disconnected the tan/black wire and it still was hard starting, maybe harder.

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92Red454SS

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I found it much easier to install the fitting at the fuel filter (out). Did I say much easier! Wow. There just isn’t any flexibility in the line at the TBI. But I did find some white crud on the high tension coil wire to the distributor..

13 psi at key on. slight drop during cranking (11), then back up to 13 when running.

Still no change in starting:(
 
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