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huh! I'll have to check that in the AM, but thanks! But I know I don't have a fuel rail, it's just a 2.5 throttle body, not multi-point.

Randy, I hear ya on the vacuum leaks with a Renix. None that I know of. And why won't it come out of open loop? I wasn't aware that the 2.5 had a fuel regulator. Where is it??

Hey Guys, I had an interesting day. I had access to a DRBII scanner, and my friend, who is an ASE mechanic (Ford) came over to figure why I'm running so rich. The scanner gives pulse width, operating temp, barometric pressure, TPS output, advance and open/close loop, among other things. I'm not coming out of open loop, even when it reaches operating temperature and beyond! My friend suspects that the fuel pump, which I had a mechanic :ack: install (see threads on stalling), is probably pumping too much fuel into the TBI. What is the right fuel pressure? Guess I'm going to have to pressure test it. If it's too high, it's going back to the shop for the right fuel pump and 4 new spark plugs :headpop: Tom

Hi, As some may know I'm having problems with the TPS, which I plan on taking care of this weekend. My friend actually has access to an MT-2500 scan tool. I'm also running rich, and failing inspection, which I never did before the rebuild, and this is with all NEW SENSORS (except the TPS). I even replaced the 02 sensor under warantee, to make sure -- I'm getting very high hydrocarbon and CO% readings. Anyway, the MT2500 won't tell me everything, I'm guessing, what help will it be in this situation? Also, there's manuals out there on the internet for testing sensors on a 4.0 RENIX system, do the same numbers apply for the 87-90 2.5 as the 87-90 4.0? thanks! Tom

anyone on the PCV or lack thereof? Rockauto lists a PCV valve for my application. :???:

Got about 750 miles on my rebuilt 2.5 now, and it's running pretty well (except the TPS problem). It's been using some oil since I first started it (changed the oil after the initial startup and at 500mi), but it's not smoking and the plugs aren't oil-fouled. I called the builder and he was surprised to hear I don't have a PCV valve, and he asked me to test vacuum at the dipstick with the vehicle running (haven't done this yet). I've had 3 MJ's with the 2.5, two manual and one automatic (86, 87, and 87) and NONE of them have had a PCV valve. I have vacuum to the rear of the valve cover, and a hose to the air cleaner at the front. I used to get blowby before the rebuild, but not any more. And no leaks! Should I be worried about the rings? This guy is a good builder. Do I just need to give it more time? On the TPS - I used to get the classical "dead spot" on the TPS, but this went away with cleaning the connectors one time. Since the rebuild I have an intermittent dead spot AND and intermittent BACKFIRE when I'm accelerating under a load (up a hill, etc). Is this typical for TPS failure? I have a buddy who has access to a MT2500 and we're going to replace the sensor one of these weekends. Just hope that's all there is to it. Thanks! Tom

fwiw I realized my prop valve wasn't working when I went through inspection and the skid pad showed that my rears weren't doing anything! I got rid of the prop valve, ran one line to the back, and plugged the bypass. What I don't like about it now is, if I brake really hard, the rears lock up before the fronts, and causes me to skid a bit. I haven't figured out what to do about this yet, but I haven't been driving like we're taught to in NJ: I'm staying off people's backs! :nuts:

http://cgi.ebay.com/ebaymotors/JEEP-AMC-DANA-20-AXLE-MASTER-REBUILD-BEARING-KIT_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116QQitemZ110251426205 Would something like this be what I need? This guy says his kit fits all amc20's from 1976 on, is he wrong? If the gears look ok, I should just leave them alone? I don't know the first thing about the guts of differentials, aside from popping off the cover and draining fluid, and changing shafts on my D35. Thanks Tom :popcorn:

Yeah, that makes sense. What axle kit/supplier do you recommend? Maybe I'll make it posi while I'm at it

I found "the last" AMC 20 from an MJ with 4.10 gears on car-parts.com. They made me a good deal, with shipping from WI, but told me it was missing the drums and "rusty." I told them as long as it turned, and wasn't rusted THROUGH, that was fine. It's not rusted through, looks straight, but there's a good amount of slop when I spin the yoke by hand. OK, so it's well-worn. My real concern was that the left axle doesn't spin. I didn't really try HARD, but it's frozen. When I spin the yoke, only the right axle spins. I'm going to try to use a breaker bar or something to free up the left one. I was hoping to buy this, sandblast, paint, new brakes/drums and go. I'm hoping I don't have to rebuild the whole thing on top of it. Is the frozen left side something to be concerned about? Thanks Tom

Thanks, guys; after reading up on it a bit, I realize it was a dumb question -- thanks again!! Tom :oops:

What controls the mixture when the truck is first-thing-in-the-morning cold? I have about 400mi on my new 2.5 with ALL NEW SENSORS (except TPS, other thread), and it runs very rich and is lopey at idle when I first start it up. It's in the 40s in the mornings here already (30s at night!). It's not stalling, or a major problem, it just seems a little rough until a few blocks of driving. Never did that with the beat, old engine and original sensors! :)

Well, I replaced every sensor on the vehicle except the TPS and it seems there's a "dead spot" in it now. Had a problem with it a couple years ago, cleaned the connectors and it cleared up. That didn't work this time, so I ordered a new Standard Ignition one. Question is - is it just bolt and go or do I need to make adjustments? Does it come preset, in other words? Thanks Tom :chillin:

Is the IAC motor working? That would be the first thing to check. If it does extend when you turn the key, turn the bolt in it out a few turns, to turn up the idle speed. I don't suppose you have a tach on the vehicle?

Possum, I used to have one of those front Smitty's. Loved it, sold the truck with it on. Do they still make them? Where did you buy yours?

My cables are intact, but the one in the cab is rusty with the floor. A while back, I looked up the applications (Raybestos) for cables, and bought two. Not sure if they are for the left and right in the rear, or if one is for the front. How are these cataloged? Rockauto still lists 2 cables for the car, under parking brake cables.

Interestingly, if you had an AW4 auto trans, it can be used behind either the 4 or 6cyl engine, with a change of bellhousing.

Pretty sure the 4.0 won't get you better gas mileage, but to answer your question, I had my 2.5 bored out and bigger pistons put in, used Yella Terra roller 1.5:1 roller rockers, K&N filter with Rusty's cone adapter, I have a header made by Clifford performance and cherry bomb muffler. You're still limited by the throttle body/injector, and I haven't heard of anything that can be done to improve fuel delivery. Mine isn't a whole lot faster than it was. It's better just by virtue of being rebuilt, but I'm not pouring any more money into it to try and gain HP/torque. It is what it is -- 151 cubes.

Just an update. This is getting hairy. I wired 12v to the pump and it ran continuously, filled a gallon container pretty quickly. I can't understand how 12V can get to the pump, the pump runs on 12V from a jumper, but the two things won't simultaneously happen. I got so fed up, I did the unheard of : Dropped it at a shop. It's a place that does inspections, so I thought I'd get the "slap a sticker" and be ok to drive for 2 years. I won't pass NJ inspection with the tires out past the flares (until I put the aftermarkets on), but at the shop it will pass the sniffer, and they'll likely let me cruise through. Pretty ashamed about dropping it off, but I was stumped and frustrated. The tech isn't having an easy time of it either, but what upset me when he called today is that he said 'your electric fan isn't working, it keeps overheating!' Naturally, with about 25 miles on the truck, I was pissed. The electric fan was working fine before it went into the shop. He claims he turned it off at 260, but I'm going to be watching the truck very closely after it gets back home. :headpop: :mad: :nuts:

try the yahoo group: 4bangerjp

hot and humid? MAP sensor?

Where is the regulator? That might be the only thing I haven't messed with.

It would kinda be unlike the ECM to partially die and improperly run the fuel pump, I would think! This is aggravating...

Does anyone know what regulates the pump coming on momentarily in the "on" position, then stopping, and coming back on during cranking? Not sure that's my problem but I think this is a more complicated circuit than the diagrams are showing. I'm tempted to take it to a mechanic, which would be the first time since I've owned it. I hate doing it, and I am new to my town, so I don't trust anybody. There was a great electrical guy near where my parents live, but that's 40 miles away, and would involve a AAA tow, so half a day! :mad:

Played with it some more this morning. It initially worked, and when I turned the key on, it pumped a few cc's into the cup I had, then stopped. When I cranked it, it filled the cup pretty briskly. Hooked the line back up, started her up, ran for a minute and stalled. No re-start. I have a relay/switch for foglights lying around -- I'm going to bypass the whole thing and see what happens. If it works, I'll make it permanent. If it continues to conk out, I'm replacing the pump. Tom