Fuel Injectors Diagnosis


TJ Enthusiast
Supporting Member
Jan 12, 2024
Ok so I am chasing a possible misfire/long crank situation. And I haven’t seen the condition of the fuel injectors. So took them out and need your wise minds to tell me what’s going on here.

Obviously they’re dirty. Not OEM. Some cracks. Some looks burnt/discolored. What causes that? Is that indicative of a problem?

If I need to replace them, since they don’t make OEM anymore, what should I be using?

I already changed the spark plugs. They were due. I tested the injectors with noise and they passed. I tested with a voltmeter and they had the same ohms.




They have definitely seen better days.
Have you observed any names or numbers on them ?
The factory PN is 53030778, but I am sure that part number has been superseded.

Extreme Terrain has replacement OEM fuel injectors for 97-02 for $115 ea.

K Suspension has Bosch 4 spray hole fuel injectors for $150 ea.

There are many sources for replacement fuel injectors online; DO NOT purchase fuel injectors on EBay. You more than likely will get the wrong flow rated injectors. Make sure you get the proper pressure rating, flow rating and electrical connector style.
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Precision Auto Injector.

Have you checked your fuel pressure?

View attachment 520373


Yes! When I prime the pump once it is 15psi. And one the second pump it is 48psi. Running it is 48psi. And I think it went down to about 30psi after 5 min of being off.

The odd thing is that it doesn’t matter if I prime the pump twice, it still cranks for a long time before starting.

I just swapped an injector placement because I had a misfire code come up and I feel like it’s running rougher while idling and driving.

So I want the rebuilt injectors? I thought I had read that there was no point in the 4 hole injectors.
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Now my codes are
P0201, p0204, p0158, p0456

I moved the badly cracked injector to 1 so that makes sense to me. Checking my connectors. And I still haven’t changed my O2 sensor it’s on the way.
There is no performance gain with the 4 (or more) hole injectors. But, if they are reasonably priced and/or more readily available, I’d buy them.

Not sure about performance injectors but heard good things about K fab.
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