91 Grand Marquis start then stall

[packman]

Does your GM spew any smoke out of the tailpipe when it runs for those few seconds? Like Gadget73 said, it could be a vacuum leak. Taking the upper plenum off can be a bitch, but replacing the lines is easy afterwards. Might want to check the PVC valve as well.



Packman

[Ringting]

I have been struggling with a 34 also. The PVC is a good one to check. The hose is shaped and cracks easily when the valve is changed a couple of times. You must basically climb up on the Plenum and look straight down between the firewall and motor to see the location. If you have not changed it then do so. It is cheap and easy (if you know where it is).

[HATNINJA]

ok now ive also changed the iac, cleaned egr which wasnt dirty, and the ignition switch. i also figgered out where the fuel pump jumper is jumped it could haer the pump whine starts for a second then stalls. FRACK!!!!! man im pullin our my hair here.

[HATNINJA]

if there is confusion i changed the ignition switch

[marquisman]

i know i asked before but, if you try starting it with your foot on the gas does it run? or does it still stall? i had a 91 colony park that had a fuged dissy and would continusly stall unless i was on the gas.

[HATNINJA]

yes

i know i asked before but, if you try starting it with your foot on the gas does it run? or does it still stall? i had a 91 colony park that had a fuged dissy and would continusly stall unless i was on the gas.

i answered this to you either here or another thread but yes i can keep it runnung when i depress the pedal till i move the pedal then it stalls what is your theory on this

[gadget73]

check the fuel pressure. The pump should run steady with it jumped out. If it quits after a couple seconds, thats the issue and a drop in fuel pressure should agree with that. Might be worth swapping the pump relay before going to a new pump. Could also try rapping on the relays with a screwdriver to see if the pump cuts in and out when you hit them. If it does, the relay is done for. I think its the green one.

[HATNINJA]

ok mmmmm

alright i changed the pickup still the same saturday im gonna take the pcm out and replace it.

[HATNINJA]

hey gadget when i jump it it runs constantly. i replaced the relay already. im gonna replace the pcm with a used one saturday unless you have any other ideas. also i had a friend start it while i sparyed starting fluid in it still the same so i guess that rules out the fuel issue.

[gadget73]

you grounded the wire at the self test connector, or you jumped the relay itself? Does the engine run with the fuel pump running constantly?

[Brandon]

I know this may be an off the wall idea here, but could it possibly be the distributor?

[Freshmeat]

Something in the distributor triggers the fuel pump relay when the rotor contacts the posts. Leave the key on and rotate your distributor to see if you can hear the relay clicking on.

[Freshmeat]

I'm surprised I haven't seen a check of the MAP sensor.

[HATNINJA]

hey gadget i jumped another wire someone told me about its a two wire connector right next to the self test connector it had an orange and a yellow one had power all the time i think ist was the yellow i cant remember what he called it i think the self prime or something like that bet it ran the pump constantly and no still the same. and no brandon ive changed the pickup and the module so i think we can rule out the dist.

[Freshmeat]

If it doesn't fix it to jump the pump then my rotor thing isn't it. Try disconnecting the MAP and plugging the vacuum to it and see if it makes any difference.