Timing vs. Idle vs. Throttle Spacer WTH?

[Schurkey]

Most (not all) diagnostic fuel pressure gauges have a button controlling a valve that leads to five feet of plastic tubing.

Push the button with the engine running, you bleed-off fuel as if the engine were under heavy load. If it maintains fuel pressure with fuel pouring out the plastic tube, you've got reasonable volume as well as pressure on that system.

Be sure the free end of the plastic tubing is dumping into a proper gas can.

The problem with TBI systems is finding a gauge that will read accurately, low enough. The TBI can run under ten psi.

https:://www.amazon.com/Actron-CP7818-Fuel-Pressure-Tester/dp/B0006V2BI2/ref=sr_1_44?dchild=1&keywords=fuel+pressure+gauge&qid=1615306867&sr=8-44

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[pmndlt]

Thanks all for the replies. So quick update, I checked for leaks and am not finding anything blatant. No random sparks or arcing.

I did remove the throttle body spacer. Starts up fine, quieter now but still within 2-3 minutes of warming up it will die in gear.

Also have noticed some backfiring. Anyhow it’s as pricey to get a gauge kit to test the TBI as it is to replace the fuel pump. So that’s the next step.

Any suggestions on whether the injectors should be cleaned? Or TBI rebuilt at same time? They have a good cone pattern. It seems to flutter?

 

[Schurkey]

I did remove the throttle body spacer. Starts up fine, quieter now but still within 2-3 minutes of warming up it will die in gear.

Is this related to the change from open-loop operation to closed-loop operation? Does it die as soon as it goes into closed-loop?

Also have noticed some backfiring.

Exhaust backfire, or backfire into the intake manifold/throttle body?

Anyhow it’s as pricey to get a gauge kit to test the TBI as it is to replace the fuel pump. So that’s the next step.

A new pump does not guarantee proper fuel pressure. You STILL need to connect a fuel pressure gauge whether or not you install a new pump.

Any suggestions on whether the injectors should be cleaned? Or TBI rebuilt at same time? They have a good cone pattern. It seems to flutter?

Probably no need to clean the injectors. Good policy is to buy Top Tier fuel, and to dump a bottle of Techron in the gas tank at every oil-change time.



Did you ever verify that the timing mark on the damper hub is in the right position?

 

[pmndlt]

Is this related to the change from open-loop operation to closed-loop operation? Does it die as soon as it goes into closed-loop?



Exhaust backfire, or backfire into the intake manifold/throttle body?


A new pump does not guarantee proper fuel pressure. You STILL need to connect a fuel pressure gauge whether or not you install a new pump.


Probably no need to clean the injectors. Good policy is to buy Top Tier fuel, and to dump a bottle of Techron in the gas tank at every oil-change time.



Did you ever verify that the timing mark on the damper hub is in the right position?

Stalling - Yes in idle it’s fine. If I throw it in drive and pedal down it will go just fine... until the first stop lol.

Backfire - TBD, just noticed it. Sounds like exhaust.

Fuel Pressure - Dammit! I had hoped it was binary.

Timing - Not yet, noticed that comment as I read back through the suggestions since last login!

Thanks @Schurkey

 

[L31MaxExpress]

Does this truck have the TH400 or a 700r4 in it? With a 700r4 randomly stalling coming to a stop, I would replace the torque converter lockup solenoid. They can fail in the on position. If it fails in the on position it will keep the converter locked up and feel like you are stopping a manual trans without pushing the clutch, stalling the engine. Sometimes they have just enough pressure to the converter circuit to load the engine down to stall without the inexperienced manual trans driver feel as well.

 

[pmndlt]

Does this truck have the TH400 or a 700r4 in it? With a 700r4 randomly stalling coming to a stop, I would replace the torque converter lockup solenoid. They can fail in the on position. If it fails in the on position it will keep the converter locked up and feel like you are stopping a manual trans without pushing the clutch, stalling the engine. Sometimes they have just enough pressure to the converter circuit to load the engine down to stall without the inexperienced manual trans driver feel as well.

@L31MaxExpress , Thanks for the suggestion I’ve got the Hydromatic 400.

 

[pmndlt]

Quick update on the problems... Fuel pressure seemed ok to me but kept stalling so I got frustrated and brought it to the dealership where I get my 2018 serviced. I asked them to spend an hour and update. The confirmed fuel pressure was ok at 15PSI, checked EGR, IAC. The tech suspected it was coil or distributor as there is no pulse when it stalls. I had checked coils with spray test and no change in function so I got a new distributor to throw in.

Today I rotated the engine to TDC (No movement on balancer so suspect the mark is correct?) and the distributor rotor points straight forward!?!? Figured i'd rotated 180% and see if there was a chance I was out but obviously same - rotor point toward the rear of vehicle.

First time I've ever done a distributor so I thought i'd ask for help before I blow 'er up lol. What's my next step please? I dont trust anything the PO did (Including the paint pen marks on the intake/distributor) Pics to follow

 

[pmndlt]

Pics..

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[PlayingWithTBI]

The rotor should be physically pointing towards the #1 cylinder, not straight forward, on TDC during the compression stroke.

 

[pmndlt]

Thanks @PlayingWithTBI that's what I had been told. So to begin I was thinking (first problem my wife says lol) of lining it up on the marks. That would point it physically towards the #1 cylinder (albeit out 180 currently) put the cap back on and the setting the timing again to see how it runs. If not then I could replace the distributor? Appreciate your help so far!

**SITREP** Moved the distributor back to "marked" location and "assumed" the lines should match up and it is now way out and will not even start. Looking for help on how to index distributor...