no start condition, no luck with the "easy" solutions

[groghunter]

'91, 2.5 'manche.

 

Problem started with engine being a bit temperamental to start:  I'd have to crank it for a few mins when it had been sitting.  after it had run for a while, it would start easily 90% of the time.  Progressed to coughing when loaded, specifically when I would downshift to engine brake, progressed from there to dying when loaded.  Took 10 mins to start from there, got it home.

 

Since then, it hasn't started once.  It's probably easier to list the things I've already done:

 

new wires, plugs, rotor, cap

 

cps was only a month old when this started, shows proper AC voltage when multimetered & engine is cranked.  Even still, took it off & ground the mounting holes deeper, still no luck

 

put a multi-meter between the coil & gnd: seems like it's doing what it should, saw as much as 17v once.  may be an artifact of my old digital meter, it was having trouble refreshing quickly enough, but I definitely saw consistent voltage spikes.

 

Refreshed grounding terminations with new ring terminals, removed the old stock battery terminals & ring terminated those wire ends too, & put new wingnut style battery terminals on

 

I get fuel spurt if I push the valve on the fuel rail after cranking.

 

It doesn't ever cough & try to start.  it just cranks.

 

So, any ideas?

 

 

 

 

 

[HOrnbrod]

Have you checked for fault codes using the key?

 

Have you checked fuel pressure while cranking with a pressure gauge?

[groghunter]

Have you checked for fault codes using the key?

 

Have you checked fuel pressure while cranking with a pressure gauge?

 

I tried the fault codes thing yesterday, didn't see any flashing.  maybe I did it wrong, I intend to doublecheck tonight or this weekend.

 

Don't have a fuel pressure gauge.  I was treating this as a likely electrical issue, based on the fuel spurt at the rail, & the lack of coughing.  I do get raw fuel odor at the tailpipe after cranking for a bit.

 

Do you ask out of suspicion that it is a fuel issue, or just to check all the bases?

[HOrnbrod]

Reading fault codes:  http://comancheclub.com/topic/28111-reading-obdi-91-and-92-mj-fault-codes/

 

It's best to verify correct fuel pressure with a gauge. Just because you have some pressure doesn't mean the engine will run. You can rent a gauge from Autozone or similar to do a check.

 

It does sound like an electrical prioblem though. I've had two no start conditions on my 91 4.0. One was a bad CPS. There's really no foolproof way you can check them with a meter on an HO. Also aftermarket CPS's are know bad right out of the box. For replacement I would recommend a Mopar unit.

 

The other no-start was caused by a bad distributor sync sensor. This showed up as a fault code. In order to replace the 91-92 sync sensor you need to pull the distributor and disassemble it completely as it sits at the bottom of the shaft. Instead of that I just use the more modern 94 and up dizzy. The sync sensor site right on top under the rotor and is easy to replace next time. 

 

From a previous post:

 

"Installed the NOS 94-99 dizzy today since I'm getting a code 54 (Distributor sync pickup - Change sync sensor in distributor). Picked up a new 94 Mopar unit for just a little more than buying a new sync pickup for the original 91 unit. Anyhow, got her in and clocked right, plugged all the wires back in, and crank/crank/crank with no start. Rechecked everything about umpteen times, even reset the dizzy using the TDC compression stroke procedure. Was getting pissed and suspected the new dizzy pickup was bad or it had a compatibility issue with the 91 system and was going to throw the old distributor back in just to see if it would start. But tried it one more time after rechecking again and mistakenly put the old dizzy cap on. BOOM, started right up instantly. The The 91-93 and 94-99 distributors are completely different. They use the same cap but the rotor is different. I noticed I had put the old cap on, the engine ran fine, and immediately deduced something might be wrong with the new cap. Clever, right? :idea:

Turned out that the carbon push button in the cap that the rotor rides on was completely disintegrated and stuck and I had an good sized air gap on the dizzy output to the coil. :doh: I guess after twenty years or so sitting on a shelf stuff happens. Three hours to complete what is normally 30 minute job. Lesson learned. She runs great now w. no more fault codes."

[groghunter]

One thing I've not been clear on with the CPS replacements is if it's really only Mopar ones that are worthwile, or if you just shouldn't buy a cheap one.  I got the more expensive one that NAPA sells, supposedly "US made" figured it was at least a better bet than a cheapy, but are those a problem as well?

[omega_rugal]

are you even getting a spark?

[HOrnbrod]

One thing I've not been clear on with the CPS replacements is if it's really only Mopar ones that are worthwile, or if you just shouldn't buy a cheap one.  I got the more expensive one that NAPA sells, supposedly "US made" figured it was at least a better bet than a cheapy, but are those a problem as well?

 

For the more "Important" sensors, like the CPS, O2, MAP, VSS, Sync; anything that can cause a no-start, or no-run / crappy run condition I always use NOS Mopar. Since they last 15-20 years originally I'll stick with NOS Mopar if I can find them. But that's just me.  :thumbsup:

 

You really need to check your fault codes too. Of course everything doesn't show up, but most problems do. The HO OBD1 system isn't like a Renix where you can test most all the sensors with a multimeter or other common test equipment.

[groghunter]

 

One thing I've not been clear on with the CPS replacements is if it's really only Mopar ones that are worthwile, or if you just shouldn't buy a cheap one.  I got the more expensive one that NAPA sells, supposedly "US made" figured it was at least a better bet than a cheapy, but are those a problem as well?

 

For the more "Important" sensors, like the CPS, O2, MAP, VSS, Sync; anything that can cause a no-start, or no-run / crappy run condition I always use NOS Mopar. Since they last 15-20 years originally I'll stick with NOS Mopar if I can find them. But that's just me.  :thumbsup:

 

You really need to check your fault codes too. Of course everything doesn't show up, but most problems do. The HO OBD1 system isn't like a Renix where you can test most all the sensors with a multimeter or other common test equipment.

 

 

Gotcha.  I'll give those ODB1 Procedures another try.

[groghunter]

are you even getting a spark?

 

 

That's the question, right?  Coil seems to be testing good, I put a test light inline on one of the spark plugs & it seemed to flash like you would expect, but I couldn't get visible spark when I pulled a plug & tried to ground it.  but I'm not confident at all that I didn't cause that myself by not doing it correctly.  I've never tried to test for spark that way before, so if there's a "knack" to it, I don't have it.

[omega_rugal]

you must see a little spark when you put  a plug near the block

[groghunter]

Finally got time + weather to line up on this, get out to the truck & give it a go.  no help though, sadly:  12 55.

 

So yea, I disconnected the battery within the last 50 keys cycles, obviously.