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Spark & Fuel For 3 sec then Nothing

T

TommyRumble

NAXJA Forum User
Location
Atlanta, GA
Driving and the jeep just died, drifted into an Advance Auto next to a Mechanic shop - convenient.

Jeep cranks, will not start.

No fuel pressure - replaced fuel pump - nothing

Swapped the relays to check pump relay - nothing

Jumped power from relay directly to pump - pump ok

Went on vacation to leave mechanic to solve - nothing
Jeep gets spark and fuel for about 3 seconds then - nothing

Mechanic couldn't read PCM - power to reader ok but will not connect with PCM

No CEL when ignition is on - bad computer? Replace computer with same year model from junk yard - nothing.

Mechanic can’t read new PCM - still no CEL visible with replacement PCM

Advice from people smarter about Jeeps than me - waiting anxiously.

Tom
 
Now, if we only knew the BASICS--year, engine, etc., we might give you some useful assistance, but we don't, so how about we just throw stuff out until something sticks!

If it is a 97+ and you can't get a scanner to connect with the PCM, then it is usually a shorted to ground crank sensor. If your gauges don't work and you are getting a "NO BUS" signal on the instrument panel, unplug the crank sensor. If the gauges then come on, replace the crank sensor and drive away.

Good luck.
 
You are throwing parts at the problem... what year?

I would almost put money on this being a '93 or earlier with a bad fuel pump ballast resistor. Your sig says 96 but the symptoms are very familiar. If so it is a 10 dollar fix to do it right or a 50 cent fix to replace the ballast resistor with a butt splice terminal, jump the ballast resistor with a piece of wire and if the problem goes away you know it is at fault.
 
What sig?

Even if it is a 96, I would bet on the shorted crank sensor based on the no spark/fuel after 3-seconds and the no scanner connect.

I have seen conflicting years for the ballast resistor, some say 93, some say 94. The 95 FSM says 94 was the last year for it.
 
errrrrrr, profile not signature. My mistake :dunce:

Yeah, not sure exactly on the year. I know 95 didn't have it and I know 93 did, haven't looked at a real live 94 since I wired up mini-man's OHC and don't recall if it had one or not.
 
Ok, profile. Yeah, you must have more energy than me, I won't look for it if the poster won't give the information.

Getting to be a real grumpy old fart.
 
Yes gentlemen. My apologies and thanks.

1996 4x4 I6

I searched before I posted and my next step was the crank sensor. I have a 94 I can have been cannibalizing parts from that I can get from.

I threw the fuel pump at it because I was leaving for the beach the next day and was going to haul a canoe and bikes. Didn't happen in my fiancés Nissan Versa.

I bought the PCM because of another post, it only cost me 20 bucks from Pull-A-Part including a warranty and they are not made any more to my understanding.

I was stranded in Pittsburgh while I sent the PCM for my 94 through Napa for a rebuild because I couldn't get one last year.

I will follow your suggestions. Thanks again.

Tom
 
20 bucks is a fair cost to throw at it... and now you have a spare, I guess. Never a bad thing.

hmmm... glad I didn't put money on that ballast resistor :eyes:
 
TommyRumble said:
Yes gentlemen. My apologies and thanks.

1996 4x4 I6

I searched before I posted and my next step was the crank sensor. I have a 94 I can have been cannibalizing parts from that I can get from.

I threw the fuel pump at it because I was leaving for the beach the next day and was going to haul a canoe and bikes. Didn't happen in my fiancés Nissan Versa.

I bought the PCM because of another post, it only cost me 20 bucks from Pull-A-Part including a warranty and they are not made any more to my understanding.

I was stranded in Pittsburgh while I sent the PCM for my 94 through Napa for a rebuild because I couldn't get one last year.

I will follow your suggestions. Thanks again.

Tom
Click to expand...

I hope you didn't salvage any "wrong" parts--OBDI vs. OBDII.

Good luck.
 
1996 year fuel pump is unique.
Not interchangeable with other years up/down as I was told. (BUT needs to be checked if that is good info!)

96= 49 psi +/- 5 psi

(MAY just be the the gauge part but.....?????)
Higher priced so take care of it!
-------------------------------
96 is first year of OBD 2

------------(Good catch Mr. JOE !)----------

Good Luck,
Orange
 
Last edited:
depends on how much of the pump you are talking about... the whole assembly with the fuel level sender is unique for sure, it's the first year of the returnless fuel delivery system and the last year of the metal tank so it's unique. I'm fairly certain it's the same old replacement pump as the previous and later OBD years however, or fairly close to it.
 
The Bosch number for 94 and 96 are the same on rockauto.com for just the pump.
 
Fuel pump was bought new - just the pump, they didn't have the assembly in stock.

PCM was from a 96 Sport I6, same as mine except it was an automatic. My 96 has an unperformed E22 recall. Figured I could get the dealer to re-flash the junkyard PCM for free if it ended up being the culprit.

Going to pull the crank sensor from the 94 now. It was replaced last year during the Pittsburgh fiasco.
 
joe_peters said:
I have seen conflicting years for the ballast resistor, some say 93, some say 94. The 95 FSM says 94 was the last year for it.
Click to expand...

The 1992 XJ I had for a short time had the ballast resistor, my 1994 does not. Both 4.0l I6.
 
Correction - I will check compatibility of crank sensors and either pull it or get a new one, after the ballast resistor if verified to not be the problem.
 
96 certainly does not have a ballast resistor... forget about that one.

Not sure if a 94 CPS will fit a 96, checking right now.

EDIT: looks like it should, unless the connector looks different. Just make sure both have the same style pins (round vs flat) and the same shape connector housing and you're good.
 
Ahhh the joys of a 96 model. Some of them have sensors that are pre 97 style, and some of them have sensors that are 97+ style. Saw plenty of this when I worked at the parts house.

My money's on the crank sensor as well. You can check them for resistance to see if they're shot. If looking at the plug on the end of the wiring for the sensor, and you think of the pins as A, B, and C looking from left to right, you take a reading on pins B and C. If you get a reading of open (nothing), it's done. Pretty sure that's how you do it...been a while since i've actually had to ohm one out (past few i've done I knew from the start they were the culprit).
 
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