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Discussion Starter #1
A few months ago my car was running perfectly until one day it wouldn't start on me at work roughly 50 miles away. It turned out that my fuel pump died. Since then, a can of worms was opened.


I got my car started by banging on the fuel tank while someone else cranked for me and eventually it started.



After replacing the fuel pump, a massive fuel tank leak appeared and the tank would leak massive amounts of fuel when full so I also needed to replace the tank.



Now after replacing the fuel pump and tank, the car is impossible to start after sitting outside 8+ hours in less than 30 degree weather. The only way to start it is by holding the gas slightly while cranking. It will reliably start every single time, but requires the pedal to be slightly pressed down, almost like a Carburetor equipped vehicle.



In my naive attempt to fix the issue, I've done the following:


* Replaced fuel pump a second time
* Replaced map sensor
* Replaced IAC valve
* Rebuilt throttle body (re-used old injectors)
* Replaced distributor rotor
* Replaced map sensor
* Replaced fuel filter


Despite all of these replacements, the car still has a rough cold start and requires the pedal to be pressed and it makes no sense to me. The only guess I have left is that it could be the K&N fuel filter that I used. I've traditionally always used ACDELCO parts, so it may be the filter requiring greater pressure than the stock one? It says nothing like that in the description but I will replace it anyway with an ACDELCO unit.

Additionally, I've inspected all of the connections at the fuel tank and I don't think it is a connection/ground issue.





Since it's been warm, the car has started exceptionally. However, the other day it came to a near stall as I was accelerating. It has only done this near stall once so I am suspecting it must be fuel related...I just don't understand. I was thinking about swapping the fuel filter as that is the only variable left from my original fuel pump replacement.



Anyway, I have thrown a bunch of parts at the problem but haven't figured it out. Anyone here with an L03/L05 powered Caprice/Oldsmobile/Buick ever experience something like this? I greatly appreciate the help.



Thanks.
 

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Check your temperature sensors with a scan tool. If the ECM thinks that it's colder than it is, it richens the mixture which follows with it starting by holding the throttle open a bit. Sometimes the sensors start to leak coolant out around the pins which corrodes the connection thereby making the resistance higher (colder). This can be intermittent as things move around and the connection improves/degrades.
 

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Discussion Starter #3
Yeah I thought about changing the coolant temperature sensor, but when I checked it, the temperature readings were normal. I will replace the sensor since I have it sitting around already.



I guess it's just a strange coincidence for everything to occur right after I did the fuel pump + tank.

The sensor wouldn't cause a near stall condition though while accelerating, so I am suspecting it is still fuel related.
 

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If the temp sensors read right (all within 5F of each other on a cold start) and when you pull the connector, everything is clean inside, probably not the issue.

Any chance the vent on the fuel tank got pinched/kinked?

Can you monitor fuel pressure? Tape the gauge to the windshield for a couple days and see what it does.
 

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If you can not monitor fuel pressure, get a fuel line set from a 91-92 FW, or a 93 FW. They both have Schrader ports on the line.

Check your PCV valve. It allows a little air into the system. It is a cheap item to replace. Another check is the ground at the thermostat housing. I had an intake manifold get eaten through, and the ground was not good. It caused restart issues after sitting for about 1/2 hour to 1 hour. It is the ground for the computer, and the O2 sensor. Check all of your engine/chassis grounds. I behind the even # bank, one behind the odd # bank, and battery ground behind the air pump.
 
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