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.
Plugs, wires, dist. cap/rotor all good
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
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.
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
I don't feel like working on anything, at this time.
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?
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.
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.
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?