Stumped

[Rock]

1989 bronco II 2.9 2wd 5 speed Ran great! Sat for 3 mos; Starts, then dies immediately; Runs with starter fluid squirted in breather. Fuel on the rail ... 1. new fuel (in tank) pump and filter. 2. new rotor button 3. tried three reman computers from NAPA, wouldn't start. Started and ran with continuos patting of gas pedal, on computer from salvage yard, coded for 89 bronco, automatic. 4. New trottle position sensor. I'm told there is a second fuel pump on the rail. I don't see it. In fact I only see one gismo on the rail between the filter and the engine and the gas line does not appear to connect to it ... HELP!!!

 

[adsm08]

Ok, since it runs with fluid that narrows your problem down to fuel delivery. New pump and filter remove the two most common culprits. Check your Fuel pressure regulator


A new computer will make it run terribly until you get it started and running for about 10 minutes. When I replaced my computer I had to hold it wide open just to get it to run long enough for the computer to adjust.

Since you have an 89, you should only have the 1 pump, so you aren't missing anything there.

 

[country0001]

Check ur ground wires. My 90 B2 would start and run until you sat in it. It would then die. It was the ground between the engine and frame. Baffled me for 2 months.

 

[Rock]

I was told that if the regulator was bad, it would drip gas when you pulled the vac hose off the back. It didn't! Can the regulator be defective, even with gas squirting from the rail valve??? Thanks Guys for the insights.

 

[BronKitis]

What about that fuel safety switch thingy (Dang name escapes me at the moment) I've never had to deal with one myself or am exactly sure how they work, but worth a shot to throw it out there I guess.... lol

 

[country0001]

What about that fuel safety switch thingy (Dang name escapes me at the moment) I've never had to deal with one myself or am exactly sure how they work, but worth a shot to throw it out there I guess.... lol

Inertia switch.

 

[jhammel85]

I was told that if the regulator was bad, it would drip gas when you pulled the vac hose off the back. It didn't! Can the regulator be defective, even with gas squirting from the rail valve??? Thanks Guys for the insights.

It can be. At least mine was. Check fuel pressure since that seems to be your problem.

 

[Ranger44]

What about the gas in the tank?

An engine doesn't like to run winter blend gas in the summer.

Simple things first. Start at the tank, and work your way forward to the engine. How old is the filter?

 

[adsm08]

If the diaphragm has become brittle without actually rupturing it could be sending emulating a low throttle position as causing low pressure.

 

[swamprat]

I would change the regulator on the fuel rail

 

[Rock]

Thanks guys! I'm buying the regulator idea also. Gotta order it, nobody had it in stock. 90.00 bucks! I hope thats finally it, cause I sure miss driving my truck.

 

[jhammel85]

oof thats expensive! Did you get the motorcraft one? Can't go wrong with that!

 

[xr75er]

can you jump and run the fuel pump thur the VIP wire at the code reader connector? If the pump runs by Key on, engine not runnig, by grounding the fuel pump VIP point to the neg battery post, then it could be the computer. it enrgizes the fuel pump relay for 2 to 3 seconds at startup. Mine was the connector to the Inertia switch. I took it off the fire wall during the trouble shooting phase and shook the switch to see if the mag ball might not be seating properly and was moving with the bouncing of the truck during a ride and noticed that the fuel pump would shut off. Took the switch off the wire connector and jumped it and shook the wires and it did the same thing. Cut the connecter out and replaced it. the circuit checks out fine. Also found another loose wire in the fuel pump relay. Fixed that and silicone the connecter at the wires.

 

[broncodw]

Check the maf sensor to make sure it is plugged properly and good part. I have been running a bronco II for 14 years and have seen almost everything. The engine will start good and run about 15 seconds wuit MAF unplugged. Has caused me trouble before especially after taking the hose off and not putting it back on before starting after maintenance.

 

[Rock]

Replaced the Fuel Pressure Reg ... Didn't fix it ... Man, I know it is something simple, but what? Runs off of ether sprayed in, so it's got ot be a fuel issue, I think!

 

[bronco_lou]

How about clogged injectors? My 4.0 sat out of the truck for some time before I got it and dropped into my bronco, started off running only on 3 cyl, then one by one over a few days of starting and letting it idle the other 3 cyl got in the game.

Just an Idea

Louis

 

[Rock]

Fellas, finally found the problem ... The MAP sensor was bad! Had a guy hook up a scanner and it coded out the Manifold Air Pressure sensor. After 10 Months, six mechanics, numerous parts swapping and internet research, I'm rolling again like a kid with a new toy.

Thanks

Rock