fixessaxes
New Member
- Joined
- Sep 11, 2022
- Messages
- 24
- Reaction score
- 11
- Points
- 3
- Location
- North Carolina
- Vehicle Year
- 1987
- Make / Model
- Ford Ranger
- Transmission
- Automatic
1987 Ranger, 2wd, 2.9. Starts and then dies 30 seconds later. I can see bubbles in the fuel line that start a few seconds after startup, increasing until its basically just air and not much fuel and then the engine dies.
Originally, I was losing power when the tank was less than half full, so I figured it was time to change out the fuel pumps. Pulled off the bed and changed out the low pressure pump in the tank, replaced the high pressure pump under the drivers side door, changed out the fuel filter as well. Inside of gas tank was clean. Truck starts fine, but starts pulling air into the fuel line shortly after start.
In this truck, the series goes:
gas tank -> low pressure pump -> line -> fuel accumulator/reservoir -> line -> high pressure pump -> line -> filter -> onwards to engine
Between the fuel accumulator and the high pressure pump, the line is translucent so I can shine a line and see the air bubbles start up shortly after startup. The line between the low pressure pump and the accumulator is opaque, so I can't see in there. I CAN detach the line from the low pressure pump and turn the key and see that the pump is working when it spurts gas out.
Other weird detail is it isn't leaking gas anywhere. Just sucking in air somewhere between the low pressure pump and the high pressure pump. The places I can think that could be it are:
- junction between line and low pressure pump
- line between low pressure pump and accumulator
- junction between line and accumulator
- accumulator itself
- junction between accumulator and line going to high pressure pump
I can see bubbles throughout the entire length of the line from accumulator to high pressure pump, so I don't think the leak is in that line.
Again, no gas leaks anywhere. Just air getting pulled in after startup. I am now thinking that the pumps were fine (although its nice to have a working fuel gauge now, so no regrets on the low pressure pump changeout at least) and that I had a small air leak that I made worse through fussing with the lines while working.
I don't imagine that there is some sort of problem with the (new) low pressure pump- if that was somehow not strong enough or stopped working after startup (remember I can detach the line and see when I turn the key that it shoots gas out) I should just lose power, not introduce air into the lines, right?
This has been a pretty annoying problem to get this far, so I figure I would ask for some wisdom or advice before I go any further. Any thoughts from anyone? Anything I am overlooking? Any easy tests I can do to narrow it down? What should I do next? I am not super experienced at working on cars, but work with my hands for a living. So I am somewhat handy, just not experienced.
EDIT FOR ANYONE WHO GETS HERE FROM GOOGLE IN THE DISTANT FUTURE:
It ended up being a broken check valve inside the fuel accumulator/reservoir. It was sealed mostly shut, allowing some fuel by so the truck could start, but then the high pressure pump would pull a bit of vacuum and the gas would "boil" in the low pressure, showing up as the air bubbles I saw in the line forward of the accumulator. As for the check valve inside the accumulator, it is not a user-serviceable part, and a rare problem. It must have been breaking slowly, and when I put new pumps on I jostled it or the new pumps were stronger or something and busted it the rest of the way. Anyhow, I took the fuel accumulator off, I am going to remove the check valve entirely, and then put it back together with a new O-ring and install an inline check valve just before the accumulator. Everything will still operate as intended, and it will be a cheap fix.
Originally, I was losing power when the tank was less than half full, so I figured it was time to change out the fuel pumps. Pulled off the bed and changed out the low pressure pump in the tank, replaced the high pressure pump under the drivers side door, changed out the fuel filter as well. Inside of gas tank was clean. Truck starts fine, but starts pulling air into the fuel line shortly after start.
In this truck, the series goes:
gas tank -> low pressure pump -> line -> fuel accumulator/reservoir -> line -> high pressure pump -> line -> filter -> onwards to engine
Between the fuel accumulator and the high pressure pump, the line is translucent so I can shine a line and see the air bubbles start up shortly after startup. The line between the low pressure pump and the accumulator is opaque, so I can't see in there. I CAN detach the line from the low pressure pump and turn the key and see that the pump is working when it spurts gas out.
Other weird detail is it isn't leaking gas anywhere. Just sucking in air somewhere between the low pressure pump and the high pressure pump. The places I can think that could be it are:
- junction between line and low pressure pump
- line between low pressure pump and accumulator
- junction between line and accumulator
- accumulator itself
- junction between accumulator and line going to high pressure pump
I can see bubbles throughout the entire length of the line from accumulator to high pressure pump, so I don't think the leak is in that line.
Again, no gas leaks anywhere. Just air getting pulled in after startup. I am now thinking that the pumps were fine (although its nice to have a working fuel gauge now, so no regrets on the low pressure pump changeout at least) and that I had a small air leak that I made worse through fussing with the lines while working.
I don't imagine that there is some sort of problem with the (new) low pressure pump- if that was somehow not strong enough or stopped working after startup (remember I can detach the line and see when I turn the key that it shoots gas out) I should just lose power, not introduce air into the lines, right?
This has been a pretty annoying problem to get this far, so I figure I would ask for some wisdom or advice before I go any further. Any thoughts from anyone? Anything I am overlooking? Any easy tests I can do to narrow it down? What should I do next? I am not super experienced at working on cars, but work with my hands for a living. So I am somewhat handy, just not experienced.
EDIT FOR ANYONE WHO GETS HERE FROM GOOGLE IN THE DISTANT FUTURE:
It ended up being a broken check valve inside the fuel accumulator/reservoir. It was sealed mostly shut, allowing some fuel by so the truck could start, but then the high pressure pump would pull a bit of vacuum and the gas would "boil" in the low pressure, showing up as the air bubbles I saw in the line forward of the accumulator. As for the check valve inside the accumulator, it is not a user-serviceable part, and a rare problem. It must have been breaking slowly, and when I put new pumps on I jostled it or the new pumps were stronger or something and busted it the rest of the way. Anyhow, I took the fuel accumulator off, I am going to remove the check valve entirely, and then put it back together with a new O-ring and install an inline check valve just before the accumulator. Everything will still operate as intended, and it will be a cheap fix.
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