96 4Runner Fuel Pump Issue (Stumped Two Mechanics)
06-25-2012, 01:43 PM
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96 4Runner Fuel Pump Issue (Stumped Two Mechanics)
Hello:
I haven't been here in a while, this forum was a life saver when I replaced the valve cover gaskets on a 96 4Runner.
Back in December of 2011, the fuel pump (as we subsequently found out) died on a cold Winter night, the vehicle was towed to a mechanic, as it was a problem I didn't want to tackle in diagnosis or repair.
A week later, they diagnosed a bad fuel pump, finished the repair, and driving home, about two miles down the road, the car dies.
Same symptoms, engine power cuts out, starter turns motor, engine won't fire.
We tow it back to the same mechanic, a week later they say it is a clogged fuel filter and replace it.
(I thought they were supposed to replace the fuel filter when they replace the pump as a matter of protocol but whatever.)
By now we are in February of this year, the car drives well for two or three weeks, and then, one night (you guessed it) power cuts out ans car won't start.
Towed for third time to mechanic, he keeps it for a week or two, and the car (according to him) "starts fine" and "drives fine" as he has tested it everyday.
He says he can't do any more , (he suggests a variety of bad sensors but he isn't sure)so we have the car towed for the FOURTH time to another mechanic.
That mechanic immediately finds that the previous mechanic had apparently dropped the tank without properly detaching the wiring and broken it.
He said the wiring harness bracket was broken as well, what was happening was that heat was expanding the connection, the wires were moving and disconnecting, thus, cutting fuel flow and engine power.
He fixes the connection and rewires the harness.
He also says the fuel pump was a cheap after market type sold by NAPA an he upgraded to one (according to him) closer to OEM standards of Toyota.
The car runs fine until about a two weeks ago ago, when I noticed a light "bucking" when gradually accelerating, nothing alarming , but similar to having the emergency brake accidentally applied lightly, a sort of resistance.
Sure enough, one day doing about 60, the engine power dies with no warning, all lights on dash come on and I coast to the side of the road.
Starter, again, turns engine, but car won't fire.
Had the car towed to the second mechanic for the second time.
The next day, of course, the car starts right up again, and two weeks later, the second mechanic has no clue what is wrong, and can't replicate the symptoms.
He is sure that wiring isn't the issue and stands behind his work.
This is beyond frustrating and expensive, if anyone has had a similar problem and resolved it, I would appreciate any suggestions.
I haven't been here in a while, this forum was a life saver when I replaced the valve cover gaskets on a 96 4Runner.
Back in December of 2011, the fuel pump (as we subsequently found out) died on a cold Winter night, the vehicle was towed to a mechanic, as it was a problem I didn't want to tackle in diagnosis or repair.
A week later, they diagnosed a bad fuel pump, finished the repair, and driving home, about two miles down the road, the car dies.
Same symptoms, engine power cuts out, starter turns motor, engine won't fire.
We tow it back to the same mechanic, a week later they say it is a clogged fuel filter and replace it.
(I thought they were supposed to replace the fuel filter when they replace the pump as a matter of protocol but whatever.)
By now we are in February of this year, the car drives well for two or three weeks, and then, one night (you guessed it) power cuts out ans car won't start.
Towed for third time to mechanic, he keeps it for a week or two, and the car (according to him) "starts fine" and "drives fine" as he has tested it everyday.
He says he can't do any more , (he suggests a variety of bad sensors but he isn't sure)so we have the car towed for the FOURTH time to another mechanic.
That mechanic immediately finds that the previous mechanic had apparently dropped the tank without properly detaching the wiring and broken it.
He said the wiring harness bracket was broken as well, what was happening was that heat was expanding the connection, the wires were moving and disconnecting, thus, cutting fuel flow and engine power.
He fixes the connection and rewires the harness.
He also says the fuel pump was a cheap after market type sold by NAPA an he upgraded to one (according to him) closer to OEM standards of Toyota.
The car runs fine until about a two weeks ago ago, when I noticed a light "bucking" when gradually accelerating, nothing alarming , but similar to having the emergency brake accidentally applied lightly, a sort of resistance.
Sure enough, one day doing about 60, the engine power dies with no warning, all lights on dash come on and I coast to the side of the road.
Starter, again, turns engine, but car won't fire.
Had the car towed to the second mechanic for the second time.
The next day, of course, the car starts right up again, and two weeks later, the second mechanic has no clue what is wrong, and can't replicate the symptoms.
He is sure that wiring isn't the issue and stands behind his work.
This is beyond frustrating and expensive, if anyone has had a similar problem and resolved it, I would appreciate any suggestions.
06-25-2012, 02:57 PM
#2
Your sure it is always a fuel related issue???:jessica:
Have any of these mechanics ever checked the fuel pressure??
How low do you run your gas tank?
Maybe the gauge is off and your running out of gas.
Maybe all the dropping of the tank and never cleaning it out has blocked the filter or the sock on the fuel pump again.
Could be a broken wire making intermittent contact :wabbit2:
Have any of these mechanics ever checked the fuel pressure??
How low do you run your gas tank?
Maybe the gauge is off and your running out of gas.
Maybe all the dropping of the tank and never cleaning it out has blocked the filter or the sock on the fuel pump again.
Could be a broken wire making intermittent contact :wabbit2:
06-25-2012, 03:13 PM
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Your sure it is always a fuel related issue???:jessica:
No, that is the reason I turned it over to the mechanic in the first place, I am assuming THEY know.
Have any of these mechanics ever checked the fuel pressure??
I assume so, but I have no idea.
How low do you run your gas tank?
Since this issue, never below a quarter tank.
Maybe the gauge is off and your running out of gas.
But the car started the next day, and every day since the latest tow.
Maybe all the dropping of the tank and never cleaning it out has blocked the filter or the sock on the fuel pump again.
Again, why wouldn't two mechanics clean the tank if need be?
Could be a broken wire making intermittent contact :wabbit2:
No, that is the reason I turned it over to the mechanic in the first place, I am assuming THEY know.
Have any of these mechanics ever checked the fuel pressure??
I assume so, but I have no idea.
How low do you run your gas tank?
Since this issue, never below a quarter tank.
Maybe the gauge is off and your running out of gas.
But the car started the next day, and every day since the latest tow.
Maybe all the dropping of the tank and never cleaning it out has blocked the filter or the sock on the fuel pump again.
Again, why wouldn't two mechanics clean the tank if need be?
Could be a broken wire making intermittent contact :wabbit2:
Thanks for the reply.
06-25-2012, 05:13 PM
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I would be shocked if a mechanic has checked the fuel pressure, because its not easy to do. And it doesn't sound like a fuel pressure related problem. Only way to check that off the list is to check it when the problem is happening.
If crude was covering the sock of the pick-up for the pump, your truck would run bad under load all the time.
I doubt it has anything to do with running the tank low. But when the truck dies on you, have you tried putting a couple of gallons in the tank?
For some reason, remanufactured fuel pumps have a bad rep, and I personally have had bad luck with them. If I had the stock fuel system, I would only buy OEM for the pump. Its worth the money to have have to deal with this kinda of a hassle.
The wiring could be an issue. It is easy for you to check to make sure the second mechanic did fix the wires correctly. Under your back seat, on the driver's side is a cover over the fuel pump. if you pull the seat and carpet up( I dont remember is there is a flap to just lift up the carpet up in that one spot, I dont have carpet to check on my own) ANYWAY there are 4 or 5 phillips head screws. Look in there and you'll see the 4 wires running to the top of the tank. Check them. Maybe take a picture. Good Luck
If crude was covering the sock of the pick-up for the pump, your truck would run bad under load all the time.
I doubt it has anything to do with running the tank low. But when the truck dies on you, have you tried putting a couple of gallons in the tank?
For some reason, remanufactured fuel pumps have a bad rep, and I personally have had bad luck with them. If I had the stock fuel system, I would only buy OEM for the pump. Its worth the money to have have to deal with this kinda of a hassle.
The wiring could be an issue. It is easy for you to check to make sure the second mechanic did fix the wires correctly. Under your back seat, on the driver's side is a cover over the fuel pump. if you pull the seat and carpet up( I dont remember is there is a flap to just lift up the carpet up in that one spot, I dont have carpet to check on my own) ANYWAY there are 4 or 5 phillips head screws. Look in there and you'll see the 4 wires running to the top of the tank. Check them. Maybe take a picture. Good Luck
06-25-2012, 09:47 PM
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I had the same issue with my 88 ford ranger. I tried to track down what it was but gave up after a while. I went through several junk yard fuel pumps and always had the same issue. With mine I was usually able to start it again after turning the key off. I assume it reset the ecu. Probally not helpful for you but maybe a few ideas.
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07-12-2012, 06:18 AM
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Thanks To Everyone
I want to thank everyone for their input.
The mechanic called to pick up the vehicle, they said they had determined the fuel pump had failed, and replaced the entire fuel pump, covering labor and parts under warranty. Third fuel pump, and according to the mechanic, a higher quality after market brand. (thus, the warranty)
The vehicle has been there for weeks, unfortunately it remains there.
I got in to start the 4Runner and the battery died, getting a boost, the car cranked and never turned over.
The mechanics opened the gas filler door, and took off and reinserted the cap, nothing.
They also pulled and reinserted the relay fuse under the hood, nothing.
Second mechanic, third pump, I really hope this can be resolved.
The mechanic called to pick up the vehicle, they said they had determined the fuel pump had failed, and replaced the entire fuel pump, covering labor and parts under warranty. Third fuel pump, and according to the mechanic, a higher quality after market brand. (thus, the warranty)
The vehicle has been there for weeks, unfortunately it remains there.
I got in to start the 4Runner and the battery died, getting a boost, the car cranked and never turned over.
The mechanics opened the gas filler door, and took off and reinserted the cap, nothing.
They also pulled and reinserted the relay fuse under the hood, nothing.
Second mechanic, third pump, I really hope this can be resolved.
07-18-2012, 03:50 PM
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Good call
BTW I have been using aftermarket Walbro pumps for years and never had a problem with one.
07-19-2012, 01:19 PM
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Issue Solved
Hello, and again, thank s to everyone for the suggestions and replies.
The mechanics deserve credit for being tenacious and tracing the issue.
It turns out that the problem was a voltage drop between the wiring harness plugs (plural) in the sending unit.
While the fuel pump had been replaced three times, the fuel filter once, and a new wiring harness installed, the old sending unit had been the culprit all along.
The mechanic was able to somehow wiggle the harnesses while the pump was running, doing that, he traced the voltage drop to the plugs in the sending unit.
So the soldered connections between the top and bottom plugs, I assume had broken.
Problem solved, runs well.
Thanks again!
The mechanics deserve credit for being tenacious and tracing the issue.
It turns out that the problem was a voltage drop between the wiring harness plugs (plural) in the sending unit.
While the fuel pump had been replaced three times, the fuel filter once, and a new wiring harness installed, the old sending unit had been the culprit all along.
The mechanic was able to somehow wiggle the harnesses while the pump was running, doing that, he traced the voltage drop to the plugs in the sending unit.
So the soldered connections between the top and bottom plugs, I assume had broken.
Problem solved, runs well.
Thanks again!
07-19-2012, 09:15 PM
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So
Hello, and again, thank s to everyone for the suggestions and replies.
The mechanics deserve credit for being tenacious and tracing the issue.
It turns out that the problem was a voltage drop between the wiring harness plugs (plural) in the sending unit.
While the fuel pump had been replaced three times, the fuel filter once, and a new wiring harness installed, the old sending unit had been the culprit all along.
The mechanic was able to somehow wiggle the harnesses while the pump was running, doing that, he traced the voltage drop to the plugs in the sending unit.
So the soldered connections between the top and bottom plugs, I assume had broken.
Problem solved, runs well.
Thanks again!
The mechanics deserve credit for being tenacious and tracing the issue.
It turns out that the problem was a voltage drop between the wiring harness plugs (plural) in the sending unit.
While the fuel pump had been replaced three times, the fuel filter once, and a new wiring harness installed, the old sending unit had been the culprit all along.
The mechanic was able to somehow wiggle the harnesses while the pump was running, doing that, he traced the voltage drop to the plugs in the sending unit.
So the soldered connections between the top and bottom plugs, I assume had broken.
Problem solved, runs well.
Thanks again!
GREAT! Glad you found the issue.....
I would assume from all of this that the very first mechanic that pulled the sending unit to replace the pump was a little rough with it. That kinda sucks.. Ohh well...
07-20-2012, 05:40 AM
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You hit the nail on the head, if not for the incompetence of the first mechanic (who we have taken our business away from) these issues may never have occurred.
The first mechanic had (according to close inspection by the second mechanic) dropped the fuel tank before properly disconnecting the wiring harness in the top and bottom.
This goes back to December 2011.
The second mechanic, in effect, had to "cleanup" after the first one.
The first mechanic emphasizes volume of business over quality and attention to detail, I have since heard that they have problems with customers returning vehicles for everything from flat tires due to improper mounting to warped rotors and uneven pads in brake work, days or weeks after the repair was done.
Even after stating he would resolve the problem, the owner (who is passing on the business to his son) never did, if it is too difficult to diagnose, he throws his hands up and quits. I once had to have a car towed from his lot to another.
Luckily, the new mechanic charges a fair price and does good work.
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