Starter issues

[project 92z]

Today I had a remote starter installed and the small illogical part of me hoped that this issue would be bypassed and go away. No such luck. In fact the problem seems worse now because I have to wait for the remote system to reset. Honestly I don't remember if I ever tried the relay or could find one labeled starter but the other possibilities were covered. I'm just hoping someone would see this bump and remember something new.

[Schurkey]

Except if the engine looses oil pressure the oil pressure switch is supposed to turn off the fuel pump even and especially if the engine is running, at least that was the original design back in the 70s. I have seen it documented both ways.

ps ok on "fuel pump relay", again I have seen both.

Look at the wiring diagram. The oil pressure switch can cause the pump to run if the other system fails. It can NOT turn the fuel pump off UNLESS the other system has failed. The fuel pump can run equally well through the relay and it's harness, or the oil pressure switch and it's harness. They BOTH have to open to shut the pump off--assuming they both work to begin with. I can't vouch for what was done on other carlines, or by hot-rodders removing an engine-driven fuel pump in favor of an add-on electric. I'm talking about first-gen W-bodies. (and also my '88 K1500) It seems to me that fuel pump relay/oil pressure switch was kind of "GM Standard Engineering Practice" at that time.

pps guess the only way to be sure is to instrument and shut the oil pressure switch off.

Or pull the wires off the oil pressure switch and see if the engine immediately dies.

[padgett]

Except if the engine looses oil pressure the oil pressure switch is supposed to turn off the fuel pump even and especially if the engine is running, at least that was the original design back in the 70s. I have seen it documented both ways.

ps ok on "fuel pump relay", again I have seen both.

pps guess the only way to be sure is to instrument and shut the oil pressure switch off.

ppps some of my terminology is from when I worked for GM and may have varied between divisions. We are in agreement on most of its purpose.

[Schurkey]

That's odd, there is a start relay to energize the fuel pump on start. Typically it runs for 2 seconds when you turn the key one

Yes. Except it's not a "start relay", it's a "fuel pump relay".

then once oil pressure comes up the oil pressure switch energizes the fuel pump.

Not exactly right. The ECM powers the fuel pump relay for two seconds when the key is first turned "on". Then the ECM shuts-off the fuel pump relay UNLESS it gets a "crankshaft is turning" signal. If the ECM gets a crankshaft-is-turning signal, it turns on the fuel pump relay as long as the signal is present. This is the PRIMARY way the fuel pump is energized. The oil pressure switch powers the fuel pump as a back-up/redundant feature should the ECM, the fuel pump relay, or the relay wiring harness fail.

Usually a long crank happens when the relay fails and the engine does not get fuel until the oil pressure exceeds 4-6 psi.

True.

If the pressure senor died it would crank and seem to catch then die.

Not if the primary system--ECM, fuel pump relay, and wire harness--was working properly.

If both the primary and secondary (oil pressure switch and harness) systems are working properly, the current draw of the fuel pump is split between the relay and the oil pressure switch based on Ohms Law. If either system fails, the other supplies all the current needed.

SO: If you fix the oil pressure switch, and the fuel pump works better, you still need to fix the fuel pump relay/harness/ECM problem, because if that worked properly, you'd never know that the oil pressure switch system had failed.

[padgett]

That's odd, there is a start relay to energize the fuel pump on start. Typically it runs for 2 seconds when you turn the key one then once oil pressure comes up the oil pressure switch energizes the fuel pump.

Usually a long crank happens when the relay fails and the engine does not get fuel until the oil pressure exceeds 4-6 psi. If the pressure senor died it would crank and seem to catch then die.

Finally you said you changed the starter. Was the solenoid changed also ? That is what usually goes "click".

ps when I had dual quads on the SBC in my Sunbird, I had to add a prime button to fill the AFB bowls before cranking. Took considerably longer than 2 seconds.

[Schurkey]

Which is a good indication that there's still something wrong with the fuel pump relay, or relay wire harness.

[robertisaar]

when the engine is running and oil pressure is above the ~4PSI the switch triggers at, current for the fuel pump is shared between the oil pressure switch and the fuel pump relay.

[project 92z]

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A buddy of mine said that after the fuel prime then the oil pump took over. Not quite sure how that works but unplugging then replacing the sending unit fixed the problem. Actually the fuel pump for blowing the fuse every time I turned the key.

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[project 92z]

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[project 92z]

Ok I found out what my problems were. The single click on the key turn was the ignition switch. The hard start, well that turned out to be the oil pressure sending unit. I also swapped out the fuel pump (original). It was maybe a lil tired and I think the baffel interfered with some power.

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[project 92z]

Ok I found out what my problems were. The single click on the key turn was the ignition switch. The hard start, well that turned out to be the oil pressure sending unit. I also swapped out the fuel pump (original). It was maybe a lil tired and I think the baffel interfered with some power.

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[cutlass supreme FE3]

Define "hard start". There's a BIG difference in the diagnosis between "starter won't crank" and "cranks but won't start".
Nobody has mentioned the neutral safety switch yet. If the starter doesn't crank the engine when you turn the key, be sure the neutral safety switch in good condition and adjusted properly.



If the fuel wasn't flowing, the engine wouldn't run and you couldn't achieve "hi rpm".

I don't doubt that the vehicle has (solvable) problems, but you might get better advice if you just described--in detail--what the symptoms are.

probably tps or mass air flow

[Schurkey]

I recently read another thread with the same issue. Turned out to be the ignition switch. After replacing the starter, battery and cables, I think I might have the same problem. My question is could the switch also create a hard start prob.

Define "hard start". There's a BIG difference in the diagnosis between "starter won't crank" and "cranks but won't start".
Nobody has mentioned the neutral safety switch yet. If the starter doesn't crank the engine when you turn the key, be sure the neutral safety switch in good condition and adjusted properly.

Especially when it's cold out, I have to keep the rpm hi until the fuel begins to "flow" on its own

If the fuel wasn't flowing, the engine wouldn't run and you couldn't achieve "hi rpm".

I don't doubt that the vehicle has (solvable) problems, but you might get better advice if you just described--in detail--what the symptoms are.

[neophile_17]

When was the last time you did the fuel filter? That's cheap and easy though not necessarily fun.

The slow warm-up sounds different than the no start unless it's ground related. I assume you replaced both block to battery and block to body or however it is in this body. There should be 2 main ground cables although one may be smaller.

[project 92z]

I recently read another thread with the same issue. Turned out to be the ignition switch. After replacing the starter, battery and cables, I think I might have the same problem. My question is could the switch also create a hard start prob. Especially when it's cold out, I have to keep the rpm hi until the fuel begins to "flow" on its own

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