Bucking E150 Van

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Jan 11, 2009 | 12:09 AM

Smokey1961

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Bucking E150 Van

I have an 86 E150 van with the 5.0 It is giving me fits. It is bucking like a vapor locking carbed motor. I have changed both fuel filters, the can type one and the tuna can type.

Checked fuel pressure and it is 37 lbs + driving and steady, rises with acceleration, pops right to 40 lbs. when key is turned on. Both tanks are full.

I hooked pressure gauge up to port and took for a drive and when it starts bucking the pressure remains steady at 35-40lbs. I pulled the codes out and they are below.

I never knew how to do this until I used the search and found out how and where the link for the codes were. I am unable to find these symptoms though. I am wondering if I am chasing a fuel problem and it is something else. It is not plug wires or plugs, the engine just flat tries to die and if I slip it into neutral it will idle and rev up but goes to bucking as soon as I put it back in gear (auto trans)

Any thoughts would be appreciated.

Thanks, Jeff

Code 31...
<TABLE style="FONT-SIZE: 100%" cellSpacing=0 cellPadding=2 border=1 table><TBODY><TR><TD><CENTER>X</CENTER></TD><TD></TD><TD><CENTER>X</CENTER></TD><TD>PFE or EVP circuit below minimum voltage of 0.24 volts.</TD></TR></TBODY></TABLE>

Code 63 <TABLE style="FONT-SIZE: 100%" cellSpacing=0 cellPadding=2 border=1 table><TBODY><TR><TD><CENTER>X</CENTER></TD><TD></TD><TD></TD><TD>TPS circuit below minimum 0.6 volts.</TD></TR></TBODY></TABLE>

Code 81 <TABLE style="FONT-SIZE: 100%" cellSpacing=0 cellPadding=2 border=1 table><TBODY><TR><TD><CENTER>X</CENTER></TD><TD></TD><TD></TD><TD>Air management 2 circuit failure (AM2/TAD).</TD></TR></TBODY></TABLE>

Code 82 <TABLE style="FONT-SIZE: 100%" cellSpacing=0 cellPadding=2 border=1 table><TBODY><TR><TD></TD><TD><CENTER>X</CENTER></TD><TD>Air management 1 circuit failure (AM1/TAB) .</TD></TR></TBODY></TABLE>

Jan 11, 2009 | 10:07 AM

Smokey1961

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Can a fuel pump be bad and still pump pressure but not fuel?

Thanks, Jeff

Jan 11, 2009 | 12:30 PM

Franklin2

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From: Virginia

Those are the codes that came up? The throttle position sensor would make it buck and jerk. If you have a lot of codes that say many sensors are "below minimum", that could point to a wiring problem, since many sensors failing at once is unusual.

Jan 11, 2009 | 01:47 PM

Smokey1961

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Thank you for your post! Yes those are the codes that came up, I did them three times. So could I assume that more than likely it may be a grounding issue? I am going out to hook up my timing light and see if I still have spark when this happens. I am also going to go over the grounds and look closely at the wiring.

I have pretty well convinced myself that it is not fuel, as it does it on either tank with no changes at all and pressure is good. Any more ideas, I'm alll eyes.

Thanks, Jeff

Jan 11, 2009 | 05:19 PM

Smokey1961

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Ok here is what I have found out today. I have to drive it at least 25 miles or so before it starts bucking. I have already determined that fuel pressure remains constant when this happens. I hooked my timing light up to it while driving and when the engine loses power there is still spark going on as the timing light doesn't miss a beat.

If I hold the throttle steady when the engine loses power and shift it to neutral (auto trans) the motor revs up instantly. As soon as I put it in gear it loses all power again. I can do this and it will do it every time when it starts bucking. When in gear after shifting from neutral it makes no difference where the footfeet is no power, but as soon as I go to neutral it comes to life. I done this several times and it was something that I could repeat every time. Hope someone can give me some things to check out now.

Thanks, Jeff

Jan 11, 2009 | 05:53 PM

pfogle

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From: Oak Harbor, OH

Ok, replace the TPS it's likely bad. This will probably cure it. The TAB and TAD (Themactor Air Bypass/Diverter) codes mean the solenoids didn't respond. They don't do anything important on that year of van anyways. The TPS seems like the culprit to me.

Jan 11, 2009 | 06:00 PM

Smokey1961

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Thanks! The TPS was somewhat suggested before. I was hoping this new info would shed more light on the problem. Now to go see how much a TPS is before I change it.

Thanks, Jeff

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Jan 17, 2009 | 03:05 PM

Smokey1961

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Follow up on my dilema,

Problem Solved!

Thank you all for the help! It is truly appraciated!

After checking all kinds of wires and ground connections I bit the bullet and bought a TPS Sensor and put it on today. Van runs like a top again and no bucking at all.

Thanks again guys!!

Jeff

Jan 17, 2009 | 03:11 PM

#10

Freaksh0w

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From: East Tennessee

I swear, I was just going to recommend going ahead and getting a new TPS. My 86 5.0 EFI did the same thing. Did you clean the throttle body out real good while you had it disconnected from the intake? Mine was FULL of crud.