Hard(er) start after fuel pump install
05-27-2011, 12:13 AM
#1
Racer
Thread Starter
Hard(er) start after fuel pump install
Recently found the problem with my bogging 88 vert - replaced the fuel pump.
Before, had no problem starting it, turned over and would catch right away. Now that I've replaced the fuel pump and sock, it turns over and catches a little later than before but if I get it up to operating temp, and have to kill and restart it, it turns over for like 5 secs before it catches.
I set the timing before the pump install (6 DTC) and have heard that timing can make this behavior.
Any ideas fellas?
Before, had no problem starting it, turned over and would catch right away. Now that I've replaced the fuel pump and sock, it turns over and catches a little later than before but if I get it up to operating temp, and have to kill and restart it, it turns over for like 5 secs before it catches.
I set the timing before the pump install (6 DTC) and have heard that timing can make this behavior.
Any ideas fellas?
05-27-2011, 12:18 AM
#2
Recently found the problem with my bogging 88 vert - replaced the fuel pump.
Before, had no problem starting it, turned over and would catch right away. Now that I've replaced the fuel pump and sock, it turns over and catches a little later than before but if I get it up to operating temp, and have to kill and restart it, it turns over for like 5 secs before it catches.
I set the timing before the pump install (6 DTC) and have heard that timing can make this behavior.
Any ideas fellas?
Before, had no problem starting it, turned over and would catch right away. Now that I've replaced the fuel pump and sock, it turns over and catches a little later than before but if I get it up to operating temp, and have to kill and restart it, it turns over for like 5 secs before it catches.
I set the timing before the pump install (6 DTC) and have heard that timing can make this behavior.
Any ideas fellas?
Might be worthwhile removing a spark plug or 2 to making a quick check there.
BR
05-27-2011, 12:24 AM
#3
Racer
Thread Starter
Sorry, I should've mentioned, I replaced the plugs, wires, cap, rotor, ICM, O2 sensor, and ignition coil about a week prior to the fuel pump. Started fine after those upgrades, just since the pump.
05-27-2011, 12:51 AM
#4
When You set the "Base Ignition Timing" on your '88 Vette,
Did you unplug the Timing connector behind or in the vicinity of the distributor ?
The connector in question has a single wire with a Brown color & very thin black trace on it.
Thin wire of 18 gauge size.
Did you unplug the Timing connector behind or in the vicinity of the distributor ?
The connector in question has a single wire with a Brown color & very thin black trace on it.
Thin wire of 18 gauge size.
05-27-2011, 01:39 AM
#5
Racer
Thread Starter
When You set the "Base Ignition Timing" on your '88 Vette,
Did you unplug the Timing connector behind or in the vicinity of the distributor ?
The connector in question has a single wire with a Brown color & very thin black trace on it.
Thin wire of 18 gauge size.
Did you unplug the Timing connector behind or in the vicinity of the distributor ?
The connector in question has a single wire with a Brown color & very thin black trace on it.
Thin wire of 18 gauge size.
05-27-2011, 09:22 AM
#7
Racer
Thread Starter
05-27-2011, 10:06 AM
#8
Pro
Member Since: Aug 2009
Location: Cincinnati OH
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I think on your year model it is just a matter of pulling the battery cable for about 5 minutes and turning on the lights to drain any residual voltage.
05-27-2011, 11:00 AM
#11
Racer
Thread Starter
The ECM/PCM "learns" fueling information based on the 02 sensor input. If you had a fuel pressure change or erratic fuel pressure you should reset the ECM/PCM so it will "learn" the new information.
I think on your year model it is just a matter of pulling the battery cable for about 5 minutes and turning on the lights to drain any residual voltage.
I think on your year model it is just a matter of pulling the battery cable for about 5 minutes and turning on the lights to drain any residual voltage.
05-27-2011, 11:11 AM
#12
Tech Contributor
Check the fuel pressure regulator. Pretty typical symptom of the regulator going bad. To check, remove the vacuum line from the regulator which is located under the plenum to the rear on an L98. You'll see the small vacuum line running to it. If there is fuel in the line, the regulator is bad. If the line is dry, the regulator is fine.
The ECM doesn't use O2 sensor data at start-up. Other than needing to reset your clock and radio station presets, disconnecting the battery will have no affect.
The ECM doesn't use O2 sensor data at start-up. Other than needing to reset your clock and radio station presets, disconnecting the battery will have no affect.
05-27-2011, 01:57 PM
#13
Racer
Thread Starter
Go out today to start it, it hard starts cold, runs for about 4 secs, I hear a faint pop, it dies, won't restart. Starter turns over, just not catching. Where do I start? I've checked all the standard dash fuses.
Update: connected my fuel pressure gauge and have absolutely 0 psi. Could the pop have been the fuel pump relay popping and would that cause 0 psi?
Update: connected my fuel pressure gauge and have absolutely 0 psi. Could the pop have been the fuel pump relay popping and would that cause 0 psi?
Last edited by Tony A.; 05-27-2011 at 02:03 PM.
05-27-2011, 04:34 PM
#14
Tech Contributor
Go out today to start it, it hard starts cold, runs for about 4 secs, I hear a faint pop, it dies, won't restart. Starter turns over, just not catching. Where do I start? I've checked all the standard dash fuses.
Update: connected my fuel pressure gauge and have absolutely 0 psi. Could the pop have been the fuel pump relay popping and would that cause 0 psi?
Update: connected my fuel pressure gauge and have absolutely 0 psi. Could the pop have been the fuel pump relay popping and would that cause 0 psi?
Do you hear the pump run for 2 seconds when you turn the key to "run"? If not, then it's the fuse, the relay, the wiring, or the pump itself. If you do hear it run then it's either the fuel pressure regulator, one or more of the injectors, or the fuel pump check valve.
05-27-2011, 04:56 PM
#15
Racer
Thread Starter
Could be.
Do you hear the pump run for 2 seconds when you turn the key to "run"? If not, then it's the fuse, the relay, the wiring, or the pump itself. If you do hear it run then it's either the fuel pressure regulator, one or more of the injectors, or the fuel pump check valve.
Do you hear the pump run for 2 seconds when you turn the key to "run"? If not, then it's the fuse, the relay, the wiring, or the pump itself. If you do hear it run then it's either the fuel pressure regulator, one or more of the injectors, or the fuel pump check valve.
Swapped out the ACDelco EP378 FP for a new ACDelco EP375 FP and she is back roaring.
Before I make a habit of replacing FP's, is there anything in particular that can ruin a fuel pump quickly?
05-27-2011, 05:43 PM
#16
good question.
Running the tank low on fuel abuses them, running them dry kills them. Gas cools and lubricates the rubber impeller inside the pump body. As painful as it is to think of an electric motor overheating sitting inside a tank full of gas and fumes, it happens.
1/4 tank is about where it starts sucking air and where the top of the pump is exposed.
Like others, I built a well for the pump to sit in so that it never is dry and is always submerged in fuel. This also allows it to pick up fuel with a low tank and cornering.
A new tank gasket is also a good idea....re-using the old gasket can result in fuel leakage around the top plate.
05-31-2011, 04:53 PM
#17
Team Owner
Think about this, IF the pump kept running all day long after it runs out of fuel, you could be right. What do you think happens when you run out of fuel? My car motor stops. When that happens, the pump stops. In fact, it is only on for a few seconds when you turn the key. If it doesn't see the engine run, the FP doesn't get energized. Otherwise, if you crashed your car and didn't turn off the motor, the pump will be fueling the engine still. That could be BAD.
If the pump runs out of gas, engine stops and pump stops. If there is gas, it will pump and cool it. If it gets so hot that it can overheat, what do you think, safety wise, of having such a hot item in an area with pressurized gasoline fumes?
05-31-2011, 08:19 PM
#18
Drifting
Is it safe to assume that the problem was that the wrong model number fuel pump was initially installed? Looks like the EP375 is the correct one for your 1988.
