89 renix hesitation 3000 rpm, backfire/sputtering
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Newbie
Joined: Jul 2014
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Model: Cherokee
89 renix hesitation 3000 rpm, backfire/sputtering
so after my 89 renix warms up it seems to not want to go above 2k-3k rpms
when its cold it seems to work fine
tps? not enough fuel pressure?
when its cold it seems to work fine
tps? not enough fuel pressure?
Thread Starter
Newbie
Joined: Jul 2014
Posts: 20
Likes: 0
Model: Cherokee
i managed to break the MAP sensor vacuum hose and the CCV(i think) hose from the back of the valve cover
i cant seem to find these on parts store websites any part numbers for those lines?
also on my way to pick up a fuel pressure gauge to check the fuel pressure
will post again with those numbers
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
I'm afraid that MAP tube is a booger. It's important and needs to be right. If the stub is broken off in the rubber plug, you need to tease the plug out of the TB and extract the broken piece. I actually used a little screw extractor, but just a little screw should work. (doesn't need left hand thread!). I pieced mine together using a couple sections of small vacuum line to splice it. I made the "L" to go into the throttle body by heating it with a lighter. A heat gun would work better as it melts through easily. The vacuum line is not an excellent fit on the tube, so I carefully put silicone on just the tube, to be sure none ended up inside, clogging it. That was a couple years ago and it actually seems OK.
That said. A guy posted an idea, using brake line. Sounded good to me untill he mentioned 3/16". Sounds a little big, Idk, haven't tried it. Maybe a smaller size would fit in the plug right.
Lastly, it may be a good idea to try to keep a downward grade from the MAP to the TB. Any fluid or condensation trapped in the line might slow down the drop in vacuum to the MAP, causing a lull in throttle response.
That said. A guy posted an idea, using brake line. Sounded good to me untill he mentioned 3/16". Sounds a little big, Idk, haven't tried it. Maybe a smaller size would fit in the plug right.
Lastly, it may be a good idea to try to keep a downward grade from the MAP to the TB. Any fluid or condensation trapped in the line might slow down the drop in vacuum to the MAP, causing a lull in throttle response.
Thread Starter
Newbie
Joined: Jul 2014
Posts: 20
Likes: 0
Model: Cherokee
I'm afraid that MAP tube is a booger. It's important and needs to be right. If the stub is broken off in the rubber plug, you need to tease the plug out of the TB and extract the broken piece. I actually used a little screw extractor, but just a little screw should work. (doesn't need left hand thread!). I pieced mine together using a couple sections of small vacuum line to splice it. I made the "L" to go into the throttle body by heating it with a lighter. A heat gun would work better as it melts through easily. The vacuum line is not an excellent fit on the tube, so I carefully put silicone on just the tube, to be sure none ended up inside, clogging it. That was a couple years ago and it actually seems OK.
That said. A guy posted an idea, using brake line. Sounded good to me untill he mentioned 3/16". Sounds a little big, Idk, haven't tried it. Maybe a smaller size would fit in the plug right.
Lastly, it may be a good idea to try to keep a downward grade from the MAP to the TB. Any fluid or condensation trapped in the line might slow down the drop in vacuum to the MAP, causing a lull in throttle response.
That said. A guy posted an idea, using brake line. Sounded good to me untill he mentioned 3/16". Sounds a little big, Idk, haven't tried it. Maybe a smaller size would fit in the plug right.
Lastly, it may be a good idea to try to keep a downward grade from the MAP to the TB. Any fluid or condensation trapped in the line might slow down the drop in vacuum to the MAP, causing a lull in throttle response.
i will try and use some of the old hard vacuum hose and fab up some new lines for myself.
got the fuel pressure gauge
power on goes to about 40ish psi
will be able to test underload after i fix these broken vacuum lines
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