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93 Crank but dies, or no start

hightime81

NAXJA Forum User
93' 4.0 with 127K, AW4, NP231, stock except for ford fuel injectors.

came out this morning to warm up the jeep and it turned over and started for maybe a second, then died. pumped the pedal a bit and tried again with the same result.

haven't done any work on it in the past 1000 miles, so i don't think i bumped something (unless it happened while driving.. IE potholes...)

bypassed ballast resistor by jumping the two lines together - no change
about to go switch the relays around to see if that is it.

other research so far tells me i need to buy a fuel pressure tester (advance and autozone don't rent, does anyone??) so that i can verify fuel pressure.

other than that, i replaced the plugs (champion truck plugs), wires, and rotor and button about 1500 miles ago and that stuff is in good shape.

i have had some intermittent issues with el-cheapo $40 walmart battery that is only 2 yrs old... so i will also try jumping it as well. connections have been renewed and cleaned recently. grounds the same.

other than testing fuel pressure, any other advice for me? i guess i could verify spec on the CPS, however, i was under the impression that CPS failure (at least at cold) was a go/no go, which makes it an unlikely suspect.

thanks for your time!
 
so switching the relays didn't help, luck isn't with on this one lol.

also wanted to point out that when i did the tune up ~1500 miles ago, i also replaced the disty cap.

so i am going to head back out with the voltage meter and check for power at the fuel pump.

anything i could be missing (other than fuel pressure test lol)? i literally just filled my tank, so i have probly 18 gallons in there and i REALLY don't want to drop it to change the fuel pump! that and is only 31 degrees outside right now!!!
 
Test the fuel pressure !!!
Put a battery powered timing light on and check for spark !!!

You need to separate the fuel issue from the spark issue.

alternative, have a buddy spray starting fluid in the intake and keep spraying once started.
See if will stay running whie spraying.

as for the fuel pump, if it was DEAD, then you would not get the engine to fire up at all the second or third time. The fuel pressure rail would have dropped to zero on first attempt. And, DEAD is different from WEAK, thus the fuel pressure test..
 
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so while i didn't check the fuel pressure (im really trying to not spend the $40 for the fuel pressure gauge), i did just check for fuel pressure at the schrader valve and literally nothing came out. so it's definitely not getting fuel, now i need to know why.

i double checked my battery and the voltage was 12, so that is fine. odd thing is that when i turn it to on, i am 99% sure that i am hearing the pump run for 2-3 seconds (initial startup run) then nothing after that.

thinking about it, i ran my tank down pretty low just before i filled up. could it have sucked up some crud and clogged the fuel filter? the fuel filter is about 3-4 years old.

what else could cause a no fuel other than a bad pump?

thanks!
 
so while i didn't check the fuel pressure (im really trying to not spend the $40 for the fuel pressure gauge), i did just check for fuel pressure at the schrader valve and literally nothing came out. so it's definitely not getting fuel, now i need to know why.

i double checked my battery and the voltage was 12, so that is fine. odd thing is that when i turn it to on, i am 99% sure that i am hearing the pump run for 2-3 seconds (initial startup run) then nothing after that.

THIS IS NORMAL, THE ECM CONTROLS THIS. YOU NEED TO CHECK PRESSURE DURING THESE 2-3 SECONDS.
BORROW A PRESSURE TESTER FROM AUTOZONE.


thinking about it, i ran my tank down pretty low just before i filled up. could it have sucked up some crud and clogged the fuel filter? the fuel filter is about 3-4 years old.

what else could cause a no fuel other than a bad pump?

thanks!

DID YOU TRY THE STARTER FLUID?

THE ECM SHUTS OFF THE PUMP AND SHUTS OFF THE FUEL INJECTOR PULSES AND SHUTS OFF THE SPARK.
IF YOU ARE LOSING MORE THAN ONE YOU ARE IN TROUBLE.

p.s., I'm not shouting, just trying to make a point before you start throwing parts at it.

If you don't want to spend money on starting fluid, remove the fuel pump relay, put a jumper in so it runs full time.
 
1. STOP P/ing into the wind. To do this you MUST be sure of the missing element--earth, wind, water, fire, actually its more like air, fuel, compression, spark all at the right place at the right time in the right amounts.

2. You can use a spare spark plug, or pull one from the engine, put a spark plug wire on it, ground the body of the plug to the engine block. Have a spare set of hands crank the engine over--HOT BLUE SNAPPY SPARK? NO SPARK? If not, resolve the issue.

3. GOT SPARK? Good, now check for fuel. You can jumper directly from the battery positive terminal to the lead off the ballast resistor to send a full 12 volts directly to the pump. Doing that the pump will run constantly even with the key off. If you do that, and there is no pressure at the rail, then you must solve that issue. As stated by a couple of others, if you have spark (see number 2 above) then you can spray STARTER FLUID into the intake and if the engine will run like that then FUEL is the issue.

4. On your 93 if the synch sensor in the distributor fails you will NOT have an injector pulse--so, you could have good pressure to the rail but no firing of the injectors. You can use a piece of hose to listen to each injector for its "clicking" sound as it fires.

A mechanics job is to determine what the problem is and resolve the problem. Do it in orderly steps. Think about what could be the issue, then CHECK or TEST that component until the problem is isolated. Swapping parts is the easy part of it, and anybody can swap parts. DETERMINING the right parts to swap, well, that is what sets "anybody" apart from everybody else.
 
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1. STOP P/ing into the wind. To do this you MUST be sure of the missing element--earth, wind, water, fire, actually its more like air, fuel, compression, spark all at the right place at the right time in the right amounts.

2. You can use a spare spark plug, or pull one from the engine, put a spark plug wire on it, ground the body of the plug to the engine block. Have a spare set of hands crank the engine over--HOT BLUE SNAPPY SPARK? NO SPARK? If not, resolve the issue.

- pulled a wire and connected another plug, in daylight, it was hard to see the spark, and you could barely hear it over the engine turning. However, it did look more like a dull yellow spark. it certainly doesn't sound hot/blue and snappy.
- i sprayed some starter fluid into the intake and it did NOT start.

3. GOT SPARK? Good, now check for fuel. You can jumper directly from the battery positive terminal to the lead off the ballast resistor to send a full 12 volts directly to the pump. Doing that the pump will run constantly even with the key off. If you do that, and there is no pressure at the rail, then you must solve that issue. As stated by a couple of others, if you have spark (see number 2 above) then you can spray STARTER FLUID into the intake and if the engine will run like that then FUEL is the issue.

-jumped the fuel pump relay and it kicked on and ran and i heard fuel running into the fuel rail. i hit the schrader valve and a very little trickled out. i only ran the pump for about 3 seconds. looks like i will be buying a fuel pressure tester after all.

4. On your 93 if the synch sensor in the distributor fails you will NOT have an injector pulse--so, you could have good pressure to the rail but no firing of the injectors. You can use a piece of hose to listen to each injector for its "clicking" sound as it fires.

- i replaced the entire disty assembly last year. it came with a new synch sensor, but its possible that it has already tanked for some reason.

A mechanics job is to determine what the problem is and resolve the problem. Do it in orderly steps. Think about what could be the issue, then CHECK or TEST that component until the problem is isolated. Swapping parts is the easy part of it, and anybody can swap parts. DETERMINING the right parts to swap, well, that is what sets "anybody" apart from everybody else.

i don't think i can rule out fuel just yet, but i need to test the pressure with a gauge.

have spark, but it seems weak, maybe just be the battery after trying to start it probably 20X today.

if i can test and rule out the fuel pressure being an issue, does that point to a bad coil or maybe even CPS (both of which can be tested to verify they are in spec with a digital MM of course!)

thanks!
 
Fully charge your battery and get it load tested before trying to run any further tests.

IF the battery won't provide enough voltage the engine management system will fail--you need 9+ volts to keep it functioning.

Yes, you can use a multimeter to test the coil and crank sensors, as well as the synch sensor in the distributor.

Here is the rub: if there isn't enough "poop" in the battery, the PCM won't function correctly. The PCM provides the energizing grounds to the ASD relay and the fuel pump relay, both of which are necessary to make the engine run.
 
thanks joe, i will take the battery to get it tested tomorrow. still going to pick up a cheap fuel pressure tester from harbor freight tomorrow i think. good tool to have handy it seems.
 
so here is where i am at.

battery was tested to be good by adv auto (12.36volts, 375 CCA), i asked them to charge it overnight and this AM it was 13.63 volts and 540 CCA.

checked spark with the battery and it still seems dull and yellow. might just be the daylight, but im certainly not hearing any snap. the coil is at an odd angle, but if i got the multimeter probes in there right, at setting ohms 200, it was open across the primary terminals, then at setting ohms 20K it read 11.4 from the primary (neg & pos) to the high-voltage terminal. unless i am miss-reading or miss-understanding (entirely possible) that means it is within spec, right?

CPS was open across terminals B and C (I checked all terminals at all ohm ranges and it just stayed at 1 (open))

TPS with ignition to on was .78 volts closed and 3.5 WOT. WOT spec said 4.78, or close... is this close enough?

replaced the fuel filter for good measure, though it looked like it was flowing fine. jumped the fuel relay pump and it kicked on and ran without issue, had a strong flow at the schrader valve (still haven't bought the fuel pressure tester lol!)

it seems that i have air and fuel and those sensors are working correctly. not sure what else could cause a weak spark?

what's next? compression test and ?

thanks!
 
Two brands of coils:

Diamond: 0.97-1.18 ohms primary; 11,300-15,300 ohms secondary.

Toyodenso: 0.95-1.20 ohms primary; 11,300-13,300 ohm secondary.

This info is from the 95 FSM, should be pretty close.
 
same as my 93' service manual. i think i am just a little unsure of my multimeter skills. for the primary, i should use the low resistance setting (200) and for the secondary a higher resistance setting (20K). which is what i did. so does 11.4 @ 20K ohm setting = 11,400? or does it mean 11.4 and my coil is faulty?
 
so pulled the coil to confirm and i got 1.17 ohms across primary and 11,400 across secondary. so that is not the culprit and it was reinstalled.

went to turn it over again and now its not turning over, pump is priming, gauges start to come on, then it doesn't turn over. using the 2000 ohm setting, i am not getting any resistance on the CPS, but everything else is checking out at this point. retested all the fuses, TPS and coil, all are good and within spec.

any help would be REALLY appreciated. i need my to be able to drive to work in an hour:(
 
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there has got to be a trick to re-installing the CPS... maybe tape it to a yard stick to guide it in? i can't fit my hands in there to guide it back into the bell-housing...

any tips?

and yes, im throwing parts at it now since everything seems to be in spec...
 
good lord.. just spent another 45 minutes in 28 degree cold trying to get the new cps installed... i think i have the top bolt threaded in, there isn't another hole slightly above that one that i could have accidentally hit instead? it seems a little high... maybe im just tired...

other than that, i will try to get the bottom bolt in tomorrow, shouldn't be too bad. the i just have to hope that was the actual problem. since nothing seemed to be out of spec...
 
I have found that its alot easier to get the CPS in and have easy access to it if you unbolt the crossmember and let the tcase and tranny hang down a bit and then put it in from the bottom. other than that i have done it from the top of the engine and just like, sat on top of the engine and stuffed my hands down inside.
 
5-90's trick is to cut out the bottom of the sensor bracket bolt holes, then you just have to loosen the bolts and slide the sensor down over the bolts, then have someone push down on it while you tighten the bolts from underneath.

No more dropped bolts, no more fighting to start the bolts.
 
$0.02:

Keep a close watch on the battery VOLTS -WHILE CRANKING.

As Joe said it MUST have good VOLTS --during cranking-- for the electronics to work at all.

In COLD weather battery's lose strength FAST. During Cold weather its much harder to turn over the engine which just makes it worser. Weak batterys hate Cold.

Go thru Joes list making sure EACH step is 'for sure right' before the next step.

GOOD LUCK,
Orange
 
alrighty. got the CPS in with a helping hand and a little flexibility! also refreshed all my battery connections and grounds (again).

Verified a hot blue snappy spark! but it is still just turning over and not catching. also wont run off of starter fluid. pulled a plug and it looked good (only 1500 miles old), maybe a bit wet from gas.

what am i missing (other than a REAL fuel pressure test, got a good spray from the scrader) ?
 
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