KurtD

My daughters truck is stalling once it gets warmed up. Let it cool down and it will start back up. Recently replaced leaking water pump and thermostat with 195 degree thermostat but ran okay for a couple of months before stalling. Checked timing and it is set correctly. Checked codes and have a KOEO 553 - AIRB/AIRD circuit shorted or open.

The temperature gauge does not work, so I don't know if it is overheating. Radiator is full and reservoir is where it should be.

I thought it might be the ECT sensor, but it seems to be working. 37K ohm when cold and around 2.7K ohm when at operating temperature.

I am thinking about putting a cooler thermostat back in and see if that helps.

Also, the valve cover gasket is starting to leak more to the point of coating the exhaust side of the motor. There is also a leak near the dip stick. Seems to be coming from some sort of sensor near the back of the motor with two wires coming out of it. Not sure if the oil leaks would contribute to stalling.

Any recommendations are appreciated.

Thanks

1992 F150 Custom
4.9L 5 speed manual
2wd

KurtD

Just took the 60 pin off the EEC to test the AIRB and AIRD circuits. Everything checked out how it should. No grounding or shorts. Put everything back together and now the truck wont start.

Checked KOEO error codes and got 553 and 542 (fuel pump secondary circuit failure). Looks like I will need to check fuel pump circuits now.

I checked fuel pressure in January with KOEO and got: 1 turn = 0 psi, 2nd turn = 10 psi, 3rd turn = 20 psi, 4 turn = 30 psi, 5 turn = 40 psi, 6 turn = 48 psi, It would hold 48 psi for about a minute ant then drop to 46 and continue to drop slowly. Engine idling = 40 psi. FPR vacuum unhooked while running = 50 psi.

Steve83

It would help if your signature contained ALL the truck's details. Click this & read the caption:


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The temp gauge is a simple system, so I'd fix that ASAP. Read this caption:


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Do not put the wrong parts in it - you'll only cause more problems. The only temp for the t'stat is 195°F.

It takes a little effort to change the VCG, but it obviously needs to be done. Read this & the NEXT caption:


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The only sensor-like object at the rear of the block is the oil pressure switch, which is known to leak & fail, but it only has 1 wire:


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An oil leak would not cause a stall until the oil level was so low that the lifters bled down to the point that they couldn't open the valves. By that time, the engine would seize. Do you keep the oil at the correct level?


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Define "won't start"... Does the key turn? Does the starter relay engage? Does the starter spin the engine? Does the engine try to run? Be specific.

Fuel pressure months ago doesn't seem relevant - check it now; preferably WHILE the symptom is present. But this doesn't seem like a fuel problem - I get the impression it's related to the ignition system, so you should follow the diagnostic procedure in Haynes Ch.5 (usually Sec.5 or 7):


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KurtD

Steve83,

Thanks for the reply.

Oil is near the full line on the dipstick, so that should not be the problem. I do need to replace the VCG and look into the temp gauge. Thanks for the information.
The starter spins the engine, but does not fire. Does not sound like it wants to fire. The fuel relay switch clicks when the key is turned on, but the fuel pump does not run. I checked at the inertia cut-off switch and there is 6 V, but reading other posts I needed a test light to check for 12 V under load. I now have a test light, and am going to check for power at the fuel pump tomorrow. I lifted the bed and put on blocks so I can access the top of the fuel tank. If there is power at the pump, and the pump doesn't run at all, seems I need a new pump.

Steve83

How exactly are you measuring this 6V at the inertia switch? Either describe where each meter probe is & the position of the ig.sw.; or post pics.

KurtD

KurtD

Steve83

Did you inspect the AIRB/AIRD (TAB/TAD) solenoids & their wiring when you took the valve cover off?


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KurtD

Took the truck for an extended test drive today and it worked the best it has since we have owned it. No hesitation while accelerating and an added bonus of no oil drips in the driveway after being parked for over an hour. The check engine light would come on and go off fairly regularly and I still got code 553 with the KOEO test after the test drive.

I did test the AIRB/AIRD circuits and solenoids. I followed the steps below I found on another website. Everything measured how it was supposed to. Both solenoids measured around 75 ohms for step 9. Steps 8, 10, 11, and 12 all measured how they were supposed to. The steps below say that if the circuits measure as they are supposed to, replace the PCM. Any other tests that can be done?

Thanks

8) Codes 81/553 & 82/552 :
Codes 81/553 and 82/552 indicate voltage output for secondary air injection solenoid did not change when activated. Possible causes for this fault are:

AIRB/AIRD circuit(s) shorted or open.
Fault in solenoid or PCM.

Disconnect both solenoid connectors. Turn ignition on. Measure voltage between VPWR terminal of wiring harness connector and battery ground for both solenoids. If either voltage reading is less than 10.5 volts, repair wiring harness open circuit, and repeat QUICK TEST. If both readings are 10.5 volts or more, go to step 9).

9)Measure Solenoid Resistance :
Turn ignition off. Leave solenoid connectors disconnected. Measure resistance of both solenoids. If either reading is not 50-100 ohms, replace solenoid assembly and repeat QUICK TEST. If both readings are 50-100 ohms, go to step 10).

10) Check Circuit Continuity :
Leave ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between AIRB test pin and AIRB terminal at wiring harness connector. Measure resistance between AIRD test pin and AIRD terminal at wiring harness connector. If either reading is 5 ohms or more, repair open circuit and repeat QUICK TEST. If both readings are less than 5 ohms, go to step 11).

11) Check For Short To Ground :
Leave ignition off and solenoids disconnected. Measure resistance between test pin No. 51 and test pins No. 40, 46 and 60 at breakout box. Measure resistance between test pin No. 11 and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short to ground and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to step 12).

12) Check For Short To Power Circuit :
Turn ignition off. Measure resistance between test pin No. 51 and test pins No. 37 and 57 at break-out box. Measure resistance between test pin No. 11 and test pins No. 37 and 57 at breakout box. If any resistance is less than 10,000 ohms, repair short to power and repeat QUICK TEST. If code is repeated, replace PCM. If all resistances are 10,000 ohms or more, replace PCM and repeat QUICK TEST.

Steve83

Since I assume you DON'T have a breakout box, how exactly did you do steps 10-12?

Have you looked inside the EEC yet?


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