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Video of the stubling bumbling AMC-2.5er . . .


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Jeez, I don't know . . .

 

I had put a 350TBI into my GTA it had a bad O2 engine ran fine just popped on the SES light and got 15mpg instead of 18mpg . . .

 

 

This thing simply won't accelerate then idles rough . . .

 

But you could be right its on the list of parts . . .

 

Say dose this neat & interesting system had a main computer unit ?

 

If so could this be malfunctioning ?

 

Mike

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Say dose this neat & interesting system had a main computer unit ?

 

If so could this be malfunctioning ?

 

Mike

 

Yes. but while it's possible that it's bad, it isn't likely. computer failures are pretty rare.

 

Also, make sure you quadruple-check for vacuum leaks. Especially at the sealing surface between the intake manifold and head.

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Straight from the FSM:

"Since fuel pressure at the injector is kept constant, the volume of fuel injected is dependent only on the length of time that the injector is energized. The injection time duration is based on engine operating conditions, which are provided to the ECU by the

input sensors."

 

You need to check your MAP, CPS, CTS, MAT, and TPS. Since the problem you are having is engine speed related I would check the CPS first and then your injector/fuel pressure regulator. Its definitely not your O2, because all it does is adjust the fuel trim depending on your current A/F ratio.

 

To check the fuel pressure, the FSM says 17.3 psi, which is to be set at 2000 rpm's. There is an 1/8" NPT allen head plug, both directly above the fuel line or 90 degrees from the line (Towards the driver fender. Recommend taking off the hat and the plate the hat clamps to so ease this process). I recommend buying a small liquid filled gauge to just leave in there.

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Throttle Position Sensor is brand new just changed it yesterday !

 

I took my fuel pressure tester back to the store as it wouldn't adapt to this truck and got the TPS with the money !

 

If the Crank Position Sensor was bad the engine would simply not run or so i was told by many.

 

The second the Map sensor is unplugged the engine stalls which i was told ment it was fine.

 

As for the rest I don't know what they are . . .

 

You gotta remember i'm used to driving 1950's 60's 70's truck's Carburated engine's with manual choke's . . . even the automatic choked carb's confuse me from time to time EFI is well beyond my understanding but i have owned a few Injected unit's i personally liked the TBI over the TPI, MPI, and SFI system's TBI seemed to be more stable and less trouble some till now . . .This is my first TBI related malfunction :fs1:

 

Sorry but i'm "EFI STUPID" . . .

 

Mike

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I'm "carb-stupid". :( efi is pretty simple to me, carbs may as well be from a crashed alien spacecraft. all depends on what you're used to I guess. :dunno:

 

Not that I think it'd change anything, but I do believe that there's an adjustment technique required for new TPSes.

 

I'd also suggest a can of gas stabilizer or octane booster. Might help if it is indeed bad gas and it's fairly cheap to try.

 

out of curiosity, do you have the original cat on it?

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There isn't a Cat ? Truck never had one when I got it ? When the exhaust shop put the new one on they didn't install one either.

 

The way it was it didn't appear there ever was one ?

 

There was no cobbled pipe making it like it was removed by a previous owner . . .

 

Ok I simply installed the new TPS as the old was set.

 

If there is a proper way of installing the TPS I'd like to know about it .

 

Mike

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We tested and tuned the TPS best we could get for numbers where .81V & 4.14V best it would get for the M/T it call for a .80V & 5.0V . . .

 

It ran great for almost a whole lap around the block then it went to stumbling but instead bogging & dogging till it stalled out 3 out of 8 times it actually caught itself and reved up then stumbled and bumbled some more instead bogging right to dead stall or idle . . .

 

Watery Crappy Fuel ? :dunno: ?

 

Mike

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while doing a quick internet search of my symptom's i found 4 reoccurring fixes . . .

 

1. TPS on EFI engines & accelerator pump on carbbed engines.

 

2. Vacuum leaks.

 

3. air intake charge temp sender.

 

4. O2 sensor.

 

5. pour fuel/ clogged filter listed a few times.

 

Mike

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:wall: Well i changed the fuel filter, added 5.2 gallons of fresh fuel, and a yellow bottle of "HEAT" and it after a while of stumbling and bumbling around i now have the use of idle up to 1/4 throttle with out any malfunction's but once i get around 1/2ish throttle it start to stumble and bumble but it doesn't really bog now but i never got on it any to see how it performed in them 3/4-WOT zone . . .

 

Good news is it went for useless to marginally drivable ;)

 

jamminz.gif Progress boys & girls progress gotta make you all feel good i'm happy at a sign of forward progress instead of another get no where money investment :clapping:

 

I think i may have a bad fuel tank or sending unit seal :???: :dunno: :???: I read that some place where a person had an issue like this turned out he had a rusty top side of the tank and dried out rotten sender seal :ack:

 

Could such a thing be happening here :???: :dunno: :???:

 

Can moisture be getting into my fuel tank ? . . .

 

 

Mike

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Weren't you bragging before about how you only use non-ethanol blended fuels???

 

Another benefit of running 10% blended fuel... Moisture doesn't collect in the tank for exactly the same reason that Heet works... The alcohol creates a chemical bond with the water and carries it through the fuel system

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:fs1: No i was bragging about using no alky fuel, Some body else was arguing with some body else over weather or not that alky or non alky fuel could be had . . .

 

I simply mentioned the Gas station on my block sold non alky fuel so that's what i was burning, not because f the fuel type but the mere location of the station . . .

 

I know i only put about a 1/2 tank of fuel in my truck at a time, Cause the tank leaks when i fill it up 5/8 of a tank as i mentioned months and months ago ;) . . .

 

Holy Kat's leaky tank + winter weather + my symptoms = :fs1: I need to get a ne rubber seal for the sending unit :fs1:

 

Now i feel stupid :doh: I bet I got WATER :thumbsup:

 

Say where can i get a new gas tank for this truck ?

 

I'm into it this deep i may as well get a new one so there is no more surprises . . .

 

Mike

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Thought your plugs looked a bit to "white", and idle fine but falling all over itself like that but not constantly made me think water in the system that will clog up a filter really fast was the culprit and why I mentioned it, specially after all your other attempts failed. Drop your tank, have it cleaned. Tank is probably ok. If you get another tank it will be used and should be cleaned before putting it in anyway. I've had to do that before.

Another thing. Current gasoline, I am told, goes bad within a month. If you store a car you need to put a fuel stabilizer in the fuel, and run it at least every month. Otherwise, you get this same problem.

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This truck gets driven every day, around my area we have alternate side parking mid Nov-mid Mar . . . So its been a real treat try to limp it from side to side only being able to idle it through this hole ordeal . . .

 

I figured i'm going through the fuel system any how may as well look at the fuel tank . . .

 

Gas TanK:

http://www.partstrain.com/store/details ... 70104.html

 

Mike

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Cool thank's, i'm sure it'll be fine tray or no tray just gotta keep gas in it . . .

 

Anywho, I got gutsy and rather then get a ride to the bank i drove the Jeep it ran great all the way there and back !

 

pulled them 235's just fine even with all the weight in the bed no power issues, Man do them Nice M/T's have a nice hum to them . . .

 

Water in the fuel was my issue trucks fixed :thumbsup:

 

Mike

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