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Hosejockey61 06-05-2012 04:35 PM

1993 YJ Starting Issue
Hi Fellow Members,

My son has a '93 YJ that is becoming very hard to get started. I have researched the posts related to the ECU as being the problem, but I'm not sure that's what it is. I don't want to do brain surgery unless absolutely necessary!

Here is a link to a YouTube video showing the issue.

We welcome your feedback and will try to narrow it down to the most likely issue. We will post our results for others having the same issue.

Thanks again for your help!

superj 06-05-2012 04:50 PM

can you write out what the issue is? i cannot watch youtube from work because its blocked. i have an office job so i have lots of time to help diagnose your trouble this evening

Hosejockey61 06-05-2012 08:53 PM

Yeah, no prob!

The facts:

Plugs, wires, dist. cap/rotor all good
Newer battery
Air filter is clean
All fluids maintained and at proper levels
No check engine light/flashing codes
It turns over just fine...doesn't struggle with that, only to get running
Started doing this out of the blue a couple of weeks ago...not cold nor hot out...nice weather
Runs fine once it starts

The problem:
When starting it, it takes 6-8 seconds to start....seems to really struggle when starting, but once started, runs fine.

My thoughts (please correct me if I'm wrong):

That it is not a fuel pump or filter as I believe that would also affect it after it is started
I'm leaning towards the ECU "brain surgery" option.

Maybe it has spring allergies....I don't know lol.

Any feedback is appreciated.

superj 06-05-2012 08:58 PM

i don;t know to much about the ecu deal but i know that some times the check valve in the fuel pump looses its ability to keep pressure and causes some long hard starts for people.

have you put a gauge on your fuel rail to check the pressure when its starting and when its off. i am not 100 percent sure on the amounts but i think i read it should be around 31 when starting and 39 when the vacuum line is removed. then its supposed ot hold pressure for 20 minutes or so when you turn it off.

sorry, mine is carb'd so i am not up on the fuelly numbers

Hosejockey61 06-05-2012 09:28 PM

Hmmm....sounds interesting enough. I haven't done that yet but will give it a good inspection tomorrow to see if there is anything obvious along the fuel line.

If it doesn't hold the vaccuum, would it still run OK once started or would that problem persist?

Que89YJ 06-06-2012 06:36 AM

If you are able to check codes the ecu is fine. If you don't get the cel light when you turn the key then the ecu is bad. I can't check codes either but the CEL light is the key. Do you have a CEL when you turn the key?

Hosejockey61 06-06-2012 09:15 AM

yes it does come on then goes off once started.

Que89YJ 06-06-2012 09:59 AM

You dont have the ecu issue then. You need to start with a couple basics. Check your fault codes and post back what you find. You should have 12, 33, and 55

Does it make any difference cold/warm start?

Check your fuel pressure. 31 psi running, pull the vacuum to the regualtor 39psi, and most important to your start issue the bleed down; shut it off and make sure your pressure stays above 20 psi after 20 minutes.

Clean your IAC and throttlebody:

Hosejockey61 06-06-2012 03:11 PM

Ok will parts store doesn't have an OBD1 tester...I'll have to find one to pull the codes.

It does not make a difference cold vs. warm start.

sentinal02 06-06-2012 05:43 PM


Originally Posted by Hosejockey61 (Post 13682127)
Ok will parts store doesn't have an OBD1 tester...I'll have to find one to pull the codes.

It does not make a difference cold vs. warm start.

read the link Que posted, you don't need a code reader in order to check OBD1 codes on the jeep.

Hosejockey61 06-06-2012 05:53 PM

I'm such a crackhead....didn't even see that! I will look when he gets home. Thanks!

Hosejockey61 06-06-2012 07:06 PM

Ok....the only thing that came up with codes is the 55. I didn't get a chance to look at the fuel line today but will report back when I do. Thanks again!

HandsOn 06-06-2012 09:34 PM

Weak fuel pressure has already been addressed, so what about a weak spark? Is that common perhaps with an older coil, or wiring that's not getting it's full current flow to the ignition? The truck is old enough now that some of those types of things might crop up now and then.
What about a faulty ECT sensor? If the computer thinks the engine is already warmed up, would the leaner mixture that causes make it take longer to start?
And last but not least... What about an ignition switch that's just on the ragged edge of failing in the start mode? Losing power to the ignition during the START process? That might not fly if these rigs still have the jumper wire from the starter relay to the ignition, but if that was no longer used by '93, maybe it's still got merit.

Haven't checked out que's linked thread yet, but thought I'd just throw out the first things that came to mind.
Good luck.


Que89YJ 06-07-2012 04:07 AM

Super Yj Handson and I are all telling you the same thing about the fuel psr. Do the test and check the bleed down time.

Hosejockey61 06-07-2012 04:40 PM

Ok....first off, the pressure test/bleed down test. Is the guage something I can get from a parts store? I'm also guessing that I hook it directly up to the valve on the fuel rail? (please excuse my lack of experience in this area!)

Next, I did a visual inspection of the fuel lines and this is what I found. Several hoses have extensive cracking. I don't smell fuel so I don't think they are leaking. Are the cracks bad enough to allow the pressure to seep through and create the problem we're having?

Lastly, so I don't have to figure it out by trial and error, anybody know the fuel line sizes for replacement?

The time now is 04:51 AM.

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