Hard(er) start after fuel pump install
Thread Starter
Racer
Joined: Apr 2011
Posts: 296
Likes: 1
From: Tipp City Ohio
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?
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
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
Thread Starter
Racer
Joined: Apr 2011
Posts: 296
Likes: 1
From: Tipp City Ohio
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.
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
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.
Thread Starter
Racer
Joined: Apr 2011
Posts: 296
Likes: 1
From: Tipp City Ohio
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.
Pro
Joined: Aug 2009
Posts: 725
Likes: 4
From: Plano, TX
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.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Racer
Joined: Apr 2011
Posts: 296
Likes: 1
From: Tipp City Ohio
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.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
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.
Thread Starter
Racer
Joined: Apr 2011
Posts: 296
Likes: 1
From: Tipp City Ohio
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.; May 27, 2011 at 02:03 PM.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
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.
Thread Starter
Racer
Joined: Apr 2011
Posts: 296
Likes: 1
From: Tipp City Ohio
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?
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
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.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
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?
