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#1
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98 GTP Starts but won't stay running
Car has been running fine it's my wife's daily driver.No issues no check engine light no previous warning. I did a web search and found the following information is this on the right track ? :
Grand Prix GTP with a 3.8 ltr supercharged. The car will start, run for about 20-30 secs., then die. Solutions (2) Known GTP problem. You most likely have a bad fuel pump resistor, which controls 2 speeds of the fuel pump. To check to see if this is the problem, there is a trick you can do and its very easy to do. Go to the attached link, and bend the tab my finger is pointing at and then plug it back in. If your car starts and runs fine, well we just solved the problem. Link ->> http://www.boredandstupid.com/relay.jpg Thanks for any help. Don |
#2
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Try unplugging the mass air flow sensor. If it runs then the sensor is bad.
my 2000 grand prix 3.8 had this problem but the engine would only run for about 10 seconds. |
#3
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When I first posted I couldn't get the link in the post above to open and a couple other post I found on line talked about the fuel pump resistor failing ,but by jumping two pins in the socket #14 on the fuse block it should run if indeed the resistor had failed. I tried tried this and it didn't work .Then I found another post that mentioned pulling the relay out of #15 and bending pin 58 on the relay so it doesn't plug into the socket.The link in my first post finally opened and in the picture it shows the relay out of slot # 15. From what I have read the 97 -00 GTPs have a low and high pressure fuel pump circuit with the resistor in place and working properly. when the resistor fails it will start and run for the 2-3 sec period but can't go into the high pressure run cycle. By bending pin 58 on the #15 relay it takes the resistor out of the loop and runs the fuel pump in the pressure mode all the time. I've read where some people have left their cars that way and others say it's hard on the fuel pump to run high mod all the time. I found one post that stated after 2000 RPM it's in high mode anyway.
My car is running with pin 58 on relay #15 out of the loop ,but if anyone has information on if leaving this set up this way will be harmful to my fuel pump please post it. Thank you for the replies .Don |
#4
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I know a fella with such a 3.8L supercharged V6. No trouble at all (YET).
Fascinating that the 3.8L engines have a history of about TWENTY differing failure modes that lead to the SAME failure; "it stalls". Well at least each model year only has concern for a couple failure modes. |
#5
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I should add I did buy a new fuel pump resistor to the tune of 56.00. The new resistor has longer lead wires and instructions to relocate it on the firewall just behind the alternator. I have two SSEIs but they don't have this fuel pump resistor.For some reason they only seem to be on the 97-00 Grand Prixs and the Buick Grand Sport
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#6
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Sorry for the late posting but I just thought this may be helpful to others in the future.
The purpose of the fuel pump resistor is to slow the fuel pump speed down in normal driving situations. The reason for slowing it down is to reduce the amount of noise coming from it. If the pump is allowed to run at full speed at idle and slow driving speeds the pump can be heard inside the passenger compartment. So they run the pump at a slower speed under those conditions. Basically it's an accoustics thing. Once at higher road speeds or wide open throttle the resistor is by-passed and the pump runs at high speed. Because of all the engine and road noise the loud pump can't be heard inside the car. Because of better insulation and other things the Bonneville doesn't need the resistor. When the engine attempts to start the pump is running in the high speed mode. But after just a second or two the engine computer (ECM) commands the pump to go to the slower speed via the resistor. If the resistor has failed the engine will stop running. Moving the resistor to the new location underhood protects if from road splash and such, thus extending it's life. Can you just disconnect the resistor connector and jumper the two pins in the other side of the connector? The answer is yes. The only thing is that you'll probably be able to hear the pump running inside the passenger compartment because the pump will be running at the faster speed all the time. No, it won't cause the engine to run rich or hurt fuel economy. However I would think that running the pump at high speed all the time would cause it to wear out faster. And with the pump being located inside the fuel tank it's not a fun job to do. Plus the resistor is far cheaper than the cost of a new pump, not to mention less labor to do. The resistor is only on the supercharged 3800 and is not used on the regular 3800 engine because it uses a lower volume non performance fuel pump which is quieter. |
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