88renix intermediate starting

here's my situation. my girlfriends 88 4.0L is at her friends house and isnt starting. it showed the same problem a couple days ago. last time, she called me and had me come over to help, once i got there i cranked just to test it and it fired right up with nothing out of the ordinary.

heres some info that will hopefully help:

-84k miles
-when the 88 does decide to start it cranks for a split second and fires right up, no questions asked
-new starter
-cranks fine
-does not try to fire or sputter at all, just cranks and cranks
-battery shows 12.7volts
-the charging system works fine
-the fuel pump does hum loader than mine (89xj) but its not horrible
-new plugs, wires and cap
-the fuel pump does runs shortly when key turned to start like normal (i did not check pressure once pressurized nor the pressure when trying to start)

i am stumped, im thinking a fualty ignition wire, fuel pump has trouble maintaining running pressure, funky injectors, crank sensor, or maybe even the map sensor. but i dont believe in throwing parts and money at a problem to fix it so id rather ask those that know more than me

i need help ASAP. im going to drive over to where its stranded, im going to check this thread once i get there and hope to find something helpful

thanks a million

you guys have saved my skin in the past, dont let me down :thumbup:

sounds like a cps
(crankshaft position sensor)

RNMedic said:

sounds like a cps
(crankshaft position sensor)

Click to expand...

another vote for the CPS...

a trick that sometimes works is to unplug and replug it.

I'm dealing with an extremely similar problem on my 87. mine will run awesome then just stall for no apparent reason and will crank but won't fire. come back an hour later and it starts like brand new.

Just found the coolant temp sensor is unplugged on mine, still waiting on an answer in another thread where that connector might have gone. All I have is a couple of snipped wires hanging out of a harness close by.

I had the same problem on my 88. After replacing TWO CPS's I was stumped.

Then I took apart the main electrical connection (The box on the firewall next to the brake booster) Inside it looked like nasty road tar and all the connections had varnish on them. I cleaned it up with brake parts cleaner all nice and pretty, and packed it full of fresh di-electric grease.

That should solve your problem.

And it was strange with the 88. If you ever parked it on any sort of incline, you had to roll it onto flat ground to get it to start.

'87 & '88's have a kit available from the dealer to wire the CPS directly to the ecu for a stronger signal. It has a CPS, a harness, and a new cover for the bell housing if you have an automatic. Kit doesn't come with directions, you have to get them printed or find a copy of the service bulletin.

success! once i found the damned cps i realised it had been replaced in the past (it wasnt covered in as much crap as everything else in the engine bay)

i tried unplugging it and plugging it back and she fired right up

i just ordered 2 new sensors from autozone. one to replace hers and one as a spare just incase this happens again.

thanks a million guys :wave1: