1990 MJ starts but won't stay running

[cruiser54]

Have you removed the distributor cap and inspected it inside?

FWIW, new plugs, wires, cap and rotor at every 30,000 mile tuneup.

[Epplebee]

42 minutes ago, cruiser54 said:

Have you removed the distributor cap and inspected it inside?

FWIW, new plugs, wires, cap and rotor at every 30,000 mile tuneup.

Thats next. I didn't think it should be an issue since the PO put all new caps, plugs and wires on it before i got it. Hasn't hardly ran since he did it all.

[cruiser54]

takes minutes to look. What plugs? What gaps?

[Epplebee]

On 3/22/2021 at 8:15 PM, cruiser54 said:

takes minutes to look. What plugs? What gaps?

Replaced plugs with proper .035 gap(po had them at .025) cap and rotor are in great shape. Doesn't seem to run as rich but still has a stumble about 1500 rpm til about 2000 rpm. My son will be home in about 3 weeks to drive this thing from Florida to Kentucky and I really need to get this thing running right but I am lost at this point.

[jdog]

Couple questions

what plugs did you put in it

 have you checked the tps?

Does it do it thru every gear? And is always at 1500-2000 or only in first gear?

 

[Epplebee]

11 minutes ago, jdog said:

Couple questions

what plugs did you put in it

 have you checked the tps?

Does it do it thru every gear? And is always at 1500-2000 or only in first gear?

 

NGK BKR5EIX plugs

TPS tested good

Every gear and sitting in the driveway. Always between 1500-2000 rpm. Idles great as does when i snap the throttle, but slightly increase throttle and stumble at 1500rpm

[cruiser54]

Remove and cap the vacuum hose to the EGR.

[Epplebee]

8 minutes ago, cruiser54 said:

Remove and cap the vacuum hose to the EGR.

PO installed HO intake and exhaust manifold so there's only EGR

[cruiser54]

If the PO used the wrong intake gasket, good chance there's a vacuum leak where the intake meets the head. 

[Epplebee]

35 minutes ago, cruiser54 said:

If the PO used the wrong intake gasket, good chance there's a vacuum leak where the intake meets the head. 

Wouldn't that cause a other issues then just stumbling between 1500-2000 rpm though?

[cruiser54]

Not if it's opening from 1500 to 2000 RPM..................

[Epplebee]

1 hour ago, cruiser54 said:

Not if it's opening from 1500 to 2000 RPM..................

Spoke with the PO, he said that he followed all of your tips to the T, including the intake gasket

[cruiser54]

Have you checked the intake manifold bolts to see if they're loose? 

Ever spray carb cleaner around potential intake/vacuum leaks at idle? 

Check the ground at the MAP sensor specifically?

[Ωhm]

3 hours ago, Epplebee said:

TPS tested good

 

TPS closed throttle voltage is a static test, used for adjusting TPS. TPS might have a flat spot (1500_2000rpms). Dynamic test requires moving TPS slowly between its lower and upper limits looking for any faulty spots. This type of testing would need analog voltmeter. Some DVOM have a BAR meter under the numeric display and read voltage 10 times faster than the numeric display. Could possibly find your flat spot there, if one does exist.

[Epplebee]

On 3/24/2021 at 7:21 PM, cruiser54 said:

Have you checked the intake manifold bolts to see if they're loose? 

Ever spray carb cleaner around potential intake/vacuum leaks at idle? 

Check the ground at the MAP sensor specifically?

YOU ARE THE MAN CRUISER!!! Only tip the PO didn't do was dizzy indexing. Set the dizzy properly and runs like a top. I want to thank you for your tips because I was going bat $#!& crazy.......once again, you are THE MAN!!!!!

[cruiser54]

4 hours ago, Epplebee said:

YOU ARE THE MAN CRUISER!!! Only tip the PO didn't do was dizzy indexing. Set the dizzy properly and runs like a top. I want to thank you for your tips because I was going bat $#!& crazy.......once again, you are THE MAN!!!!!

 

You hung in there!! Congratulations.