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1990 RANGER, Starts and Dies in 15 seconds


John B

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I need help urgently as I start a new job 30 miles away and am down to one car and have no way to get there. I have put all new tires on it as well.

Symptom:
The truck will start, run 15-20 seconds, I can drive it maybe a block if I am real quick. Doesn't cough or sputter just stops.

What I have done:
  • Replaced the Idle air valve
  • Replaced the fuel filter
  • Truck started and idled fine for about 15 minutes, SUCCESS!! Shut it down. Later went to go some place with it and the truck started and idled fine, but no fan for the heater. Popped the hood, rapped the blower motor and it started and the truck died. Restarted fine and died at the end of the driveway, about 20 feet. Exhibited the same symptoms. The inertia switch did look like it was hitting something hot but the switch tested fine. I am an electrician by trade.
  • Took it into shop, they thought the inertia switch was bad. I jumpered it for testing and still have the same issue. They wanted $600 to check the fuel pump
  • Changed the fuel pump relay, no change, runs 3 times and then needs to sit for few minutes before it will start again. I did notice that a ground wire was disconnected by the power distribution module, looks like it came out of the lug.
There are times when it will start once and then I have to remove the inertia switch jumper and it starts right up and runs for the typical 15 seconds or so, then by the third time it needs to sit for a few minutes.
I have NOT tested the fuel pressure because it does run.
When is stops it just stops, no sputtering or coughing.

Some history as well:
I did change the starter relay and when I did (this was the third time) I noticed that the lug from the battery to the relay looked like it had gotten hot so I changed the wire. It had run for a month or more like this. I suspect that I had a ground from this bad connector and it had damaged the relay.
The fuel pump has been replaced 2 times, once by taking off the bed for sure. But it ran for a long time this way.

Not sure what to do next…
 


Rock Auto 5% Discount Code: F9A1A579ACFAD1: October 1st, 2021

RonD

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2.9l engine?

Just to take it off the table, on the fuel rail you will have a Fuel Pressure Regulator(FPR) it will have the Return fuel line connected and a Vacuum hose.
Remove vacuum hose at FPR end and check it for fuel, shouldn't be any.
Plug the vacuum hose, with screw or bolt, now when engine starts it won't pull open the FPR valve, see if engine runs longer, easy free test.

Fuel Pump relay, look near the power brake booster for the OBD connector, it is loose not attached to anything
Look here for image: http://www.therangerstation.com/tech_library/OBD_I.shtml

second drawing down
You see the Fuel Pump slot IDed
If key is on and you GROUND that slot, the fuel pump relay will activate and fuel pump will be on and stay on, normally it only runs for 2 seconds, and computer won't start it again until engine starts, RPMs above 400
This would test if fuel pump circuit is the issue.
Also run fuel pump for 30 seconds, engine off, then test fuel pressure by pushing on schrader valve center pin, should be 30psi pressure in there, so like air pressure in a tire, run pump again. 10 seconds is fine.
Now wait 5 minutes, engine and pump off, and test again, should still have 20-30psi pressure, normally it would hold pressure for months.

Start engine, with Ground jumper in place and fuel pump running full time, rev engine or whatever to do to get it to stall.
After it stalls you should STILL HEAR the fuel pump running, if you don't then something is cutting power to fuel pump relay(green base).

Fuel pump Relay is powered by EEC relay(brown base), EEC relay also powers spark system, fuel injectors and the EEC(computer), EEC relay closes when key is turned on.
If it should open, deactivate then everything turns off



Next would be the TFI ignition, trouble spot on older Rangers

Have a read here: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

Starting and dying is one of the failure modes
 
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John B

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Thanks

I will give these a try in the morning. thanks for the pictures as well.
 

John B

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Yes it is the 2.9L

Sorry, missed this in your post, yes it is the 2.9L
 

John B

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UPDATE

Truck did start this morning after a couple of failed attempts. The only new thing is that it runs for 5-10 seconds before stopping.

Removed vacuum line from PRV and plugged it, truck started and idled faster and died quickly. No fuel in the vacuum line either. This looks relatively new, no grease or gunk built up on it, still shiny out of the box looking.

Jumped the FPRelay to ground, couldn't hear pump. The truck started on the second try with the FPRelay grounded and it ran for a couple of seconds. I can hear the relay pick-up and it is much newer as well. Deja-vu that this has been a recurring problem, new FPRelay and Fuel Pressure Regulator, seems odd.

Fuel pressure is being tested now. Will post results once I have them and see what direction that leads to.
 

RonD

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If key was on then when you grounded FR relay at OBD connector you should have heard fuel pump come on, or at the very least heard the FP relay click.
Circuit is very simple.

If you hear the FP relay click but fuel pump doesn't come on then problem will be in the wire from FP relay to Fuel pump or fuel pump itself.
Could be loose connector that is connecting briefly when starter motor is active and truck vibrates.

If FP relay doesn't click(key on/grounded) then swap EEC relay, the EEC relay should click when key is turned on, that powers FR relay and the other engine electrics.
 
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John B

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The relay cycles but the pump doesn't appear to come on. I do get some fuel sometimes because when I tested for pressure I did get a little, not enough to read on the gauge but enough to spurt out when I pushed on the schrader valve.

I will trace the wiring to the pump and see if I can find anything wrong on that path. I have found other bad connectors so that makes sense.

Thanks for the help!!
 

RonD

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Fuel injectors need minimum of 20psi on your year, later models, 1998 + needed 45psi min.
Yours should be 30-42psi

Fuel injection engines also don't usually sputter like a carb engine would do when out of fuel, they just die.
 

Big Jim M

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John I know you THINK there is 1/2 tank of fuel in there. Have you thought of pouring a few gallons more in the tank just to make sure? Might just solve your problems.
Big Jim
 

black_demon69

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check intake hose between MAF sensor and plenum (upper intake) for cracks if it has a large enough crack it would be just like a very large vacuum leak.
 

enjr44

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It ain't going to run until you have constant fuel pressure. Period, end of story.

It sounds to me (because it starts) that there is fuel pressure at the beginning; but, no pressure/flow to keep it running. A clogged fuel filter will allow initial pressure to build; but, as soon as the engine start and "flow" is needed the pressure in the rail will drop below the 20 psi needed to keep it running.
 


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