1986 Manche, Surging And Cutting Out.

[NW Mossback]

So i've got an 86 MJ 4x4, 5spd, 2.5 4cyl. 157,xxx miles. Had it for about a year now, but only been on the road for 2 months or so. So ALL the bugs are coming out of the wood, it hadn't been run consistently for years. Kinda new to the Renix system, learned quite alot in the past month, so far i've done quite alot of work to this truck.

 

First I did a full tune up. Plugs, wires, cap, rotor, fuel filter, air filter, oil and filter. That made it "Better" but still wasn't up to par yet, so then i replaced the tps which made it a bit better, along with the map sensor had it running pretty good.

 

Then 2-3 days after the two sensors it started to run really bad, i was digging around the TB and found the WOT sensor and the ECT sensor were plugged into each other...found the correct plugs coming off the harness and plugged them in and wala! Running like a top, also put a new O2 in that same day.

 

2 days later it is surging while going down the road at all speeds, and when at 1/2 throttle 3 gear on longer steepish hills it wants to cut out.

I'm all thought out here fellers, if anyone has some advice please chime in. Much appreciated.

[Harley]

Looks like ya covered everything but the coil. I'd swap that out for gits and shiggles.

[MJRemi]

CPS maybe? I think Hornbrod had a tech write-up on that.

[sin3kal]

I'd give your vacuum lines a good going over. Make sure that they have cracked and started leaking or knocked loose.

[NW Mossback]

Well good news! I got to messing around with a can of starting fluid and found a BAD leak on the 1-2 cyl intake, and a little one on the vacuum block/manifold thing on the side of the TB. Replaced the gasket along with another fuel filter just for the heck of it and now its running good. Still have a miss at idle but that might be because of the vacuum thing on the TB.

 

Thanks for the input guys, much appreciated!

[cruiser54]

Well good news! I got to messing around with a can of starting fluid and found a BAD leak on the 1-2 cyl intake, and a little one on the vacuum block/manifold thing on the side of the TB. Replaced the gasket along with another fuel filter just for the heck of it and now its running good. Still have a miss at idle but that might be because of the vacuum thing on the TB.

 

Thanks for the input guys, much appreciated!

 

Loose manifold bolts are very common on both the 2.5 and 4.0.

 

Check/replace the vacuum lines on the intake manifold just below the throttle body .