Friend's 1999 Explorer sport shuts off every two blocks.

[dani9678]

I'm getting ready to look at a friend's 1999 Explorer sport with the 4.0l 6. He says that while driving, it shuts off every two blocks. He said that he replaced the MAF sensor which didn't fix it. I need some pointers as to what to look for when I get there. Do you think it could be the ignition switch? I wouldn't think it would be the fuel pump if it starts right back up every time.

Thanks

Matt.

 

[swshawaii]

Check engine light or trouble codes? Sounds more like a fuel issue. Fuel filter and inertia cutoff switch checked?

 

[dani9678]

Ok here is what I have found. The fuel filter had just been replaced and the fuel pump assembly had been replaced over 1-1/2 years ago. The engine was over a gallon low on coolant. After I put coolant back in it, it didn't shut off anymore but still has the hard start issue. I connected a fuel pressure gauge to the fuel rail test port and found that while cycling the key to the start position, by the time the fuel pump cycled back off, the pressure would only build to 12 psi. While trying to start it, I found that the pressure would slowly build and once it reached 15 psi, the engine would start but the pressure wouldn't exceed 25 psi. I decided to check the pressure coming off of the fuel filter and found that while cycling the key to build pressure, it didn't exceed 27 psi. The owner said that it has had the hard start issue for a couple of years. She said the problem she was having was with it shutting off every two blocks. That problem went away after I topped off the cooling system. I don't know how that would make a difference since I don't believe there is an overheat shut-off feature to the engine and this was happening even on cold starts. I believe it has a return-less fuel system since I couldn't find a return line from the fuel rail to the tank.

Upon further investigating, I found that it is return-less and it sounds like the regulator is stuck open. I'm going to drop the tank and try to clean the valve to see if I an clear whatever is sticking it open. If not then I'll be replacing the entire fuel pump assembly.

Matt

 

[dani9678]

Well, I found the problem. After dropping the tank and pulling the fuel pump assembly, I found that the pressure regulator had popped out on one side causing most of the fuel to dump right back into the tank. What happened is the plastic collar had broken on one side where the metal clip slides over the regulator and through the slots in the collar. What I ended up doing is using some nylon zip ties to pull down on both sides of the metal clip to retain the regulator from popping out again. After I got it back together and tested it. I jumped the pump directly off of the battery and found that it wouldn't exceed 45 PSI and wasn't building enough pressure to open the regulator bypass. So no fuel was dumping back into the tank. I put it all back together and mounted the tank, reconnected the pressure gauge to the fuel rail port. I then had my uncle start the Explorer and found that the pressure climbed just over 50 PSI. I don't understand how it increased further in pressure while the engine was running but it still wasn't building enough to dump fuel back into the tank. I understand that it's suppose to be around 65 PSI +/- 8 PSI. It was running much better than before and would start up immediately rather then take around 5 seconds of engaging the starter like before.

Matt

 

[koda2000]

i don't know how those zip ties will hold up to gasoline. you might want to try soaking some in a jar and see what happens after a few days. if i went through as much trouble as you did, i'd have replaced the complete in-tank fuel pump assembly and be done with it. even if the fix holds, your pressure is still low.

 

[dani9678]

I gave them that choice to either go with this or to go ahead and swap out the unit for $240 and they chose to go with the zip tie mod. I did look into the "zip tie vs. gas" option and found that if they are nylon then they will be safe to use as long as the ethanol concentrations do not get to high.

 

[koda2000]

I gave them that choice to either go with this or to go ahead and swap out the unit for $240 and they chose to go with the zip tie mod. I did look into the "zip tie vs. gas" option and found that if they are nylon then they will be safe to use as long as the ethanol concentrations do not get to high.

you can buy the whole assembly starting for under $100 on RockAuto. a pretty good unit for around $125. well worth it for reliability imo. now, if it craps again you (or someone else) is going to have to go through all the time/labor to drop the tank again, but i guess it's their money.

 

[dani9678]

They needed it on the road ASAP so I did what I could to get it there and they were not up for waiting on the part to ship.

 

[Dave 1955]

You're a good guy for working on it. Cheers!
Thing may run forever now!

 

[dani9678]

I found out tonight that shortly after they left, the heater control valve split and it lost coolant. They were able to get another valve from one of the auto parts stores for around $20, they swapped it in, topped off the coolant and were back on the road. She said that before I fixed it, and while it was still drivable, she couldn't get over 30 MPH going up the Dames Point bridge here in Jacksonville, FL with it on the floor. Now she said that she can go up the bridge at 68 MPH with about 3/4 throttle. She is very happy she says.

Matt