1999 d1 start stall - may have found my problem

[blackandtandisco]

Im new to the forum, i bought a '99 D1 a few months ago. Much better than any jeep ive had. A few days ago it would start and run for 5 seconds then stall. It became an intermittent problem- it would run no problem then just stall... start/stall. i did a lot of searching on various LR websites. I started compiling tidbits of info from different posts, posts that went nowhere, OP's that ignored advise and just replaced parts...ect. This is a long post but i figured it might help someone else diag. their problem. So... start/stall, no check engine light, 20psi fuel pressure 1 Replaced fuel filter- could not break the fittings loose even after PB blasting for 2 days. Grabbed a different fuel filter with nipples and used rubber hoses. Ordered a Fuel filter kit from AtlanticBritish. 2 Before the filter was connected i had a helper turn the key to ON. Pump primes, helper tries to start, Pump does nothing. 3 Check the fuel pump fuse(engine bayright side) and inertia switch (right side of firewall)-good. 4 Checked for Spark- I belive no fuel AND no spark could be a crankshaft position sensor. From what ive read if you have spark then its probably not the CKP. 5 Check for power at the pump. Pulled up the rear carpet, mangled the rusty cover plate. Backprobed the white and purple wire (Power) with a paperclip- key on 12.6V for a few seconds then zero. Should have power while cranking but i had nothing. 6 Check MULTIFUNCTION FUEL RELAY under hood. I am not sure which years have this. It is next to the fuses. I had 12.6V on one white/purple wire but not the other. Also checked with key on and while cranking- nothing. I could not find anything on how to bench test the relay. I did find a post on taking a utility knife cut around the edge and pop the cover off the base. Once inside i checked for any damage, burn marks. I lightly cleaned the contacts of each of the 3 relays. I re-installed the relay and the truck started and stayed running. Just for reference while running i had 13-14V at both White/purple wire under the relay, and the same at the fuel pump. Ordered a new multifunction relay from AtlanticBritish. Drove the truck all day today and after a few hours it started doing it again, went right to the relay. With the truck running if i wiggle the smaller connector (even just a little bit)the truck stalls. One of the tabs to hold the connector is broken, hopefully the new relay will solve this problem.

[psykokid]

Sounds like you've tracked it down to a flaky relay or connector.. Fuel pressure sounds a bit low, should be 2.3 to 2.5 bar which is approx 33-36 psi. Voltage sounds fine as far as running vs non running.

[Spike555]

WOW!! Great job on the diagnosis!!

[leadfoot]

Thanks !!!!!!!! Good job. My teen daugthers drive the D1 and they have been complaining about the car stalling at stop lights. There is no CK light on and when I have driven it, it has run normal. I replaced O2 sensors (then it had a ck light on and a code) replaced spark plugs and wires. Ck light went off but the intermitent problem of stalling persisted. I guess I am going to check the relays now. By the way, my fuel pump has less than 10K miles on it, so I don't suspect that. But I don't see how the relay would only affect when the car stops. If the relay is failing, it would produce some kind of misfire or something while the car is moving.

[Savannah Buzz]

Since relay is an electrical device, the slightly higher voltage when speeded up may be making the difference, it might just take a fraction of a volt. Volts drop slightly when truck is at idle.

[blackandtandisco]

Installed my new relay and havent had any issues.
It seems like that fuel relay can intermittently cause problems, mine just seemed to be a loose connector- even the slightest movement caused the truck to stall.
I would invest in a fuel pressure guage and drive your daughters truck around untill stalls, and see what the fuel pressure is.
Also if you replaced the fuel pump, i assume you replaced the fuel filter- most people including me could barely blow thru the old filter.

[leadfoot]

Thanks Blackand....... that is a good idea. I do have a fuel pressure gauge, I am going to use it.