inertia switch?
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Joined: Aug 2005
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inertia switch?
Please forgive my ignorance, I have just enough mechanical knowledge to really mess up my van and not enough money to tow it to a pro. More importantly, without my van I'm going to start having real money problems soon (funny how the boss expects you to show up every day).
This is a new thread to the on-going saga of my not being able to start my 91 E150. It is a 5.0L EFI, dual tanks and AT (if the tranny type makes a difference). I started having problems with not being able to start it about a week ago. The engine rotates freely and I have spark, so I began checking the fuel. After trying repeated to start the van on either tank, I replaced the fuel relay and filter. This did not fix the problem.
So I started pulling fuel lines. Since I don't have a pressure gauge, I can only test the lines with my eyes and a glass jar. The lines are all wet, but no real "splurting" of fuel as I would expect with the key on. Even after pulling a line and testing it in my jar, then reconnecting trying to start and pulling it apart again, the line is wet... I think this means I am getting SOME fuel from the tanks, just not enough.
I started with the inlet and return lines to the rail. The line leading into the regulator (is this the inlet side?) was wet and the other (return?) line had more fuel. I pulled the line leading from the inlet of the HP in line pump... same condition at each connection all the way back to the inlet side of the selector switch (I think... thing with four lines leading into and out of). The line was full of fuel, but no real volume. I hear a click at the tanks, but cannot hear any of the pumps engage (although I never could even when it ran fine) and cannot feel the high volume pump trying to operate.
Next, I tested for power at the high volume pump, I found none on either side of the connector. I checked for power at the relay, it tests fine. On a whim, I turned the key off and checked continuity between the positive and negative sides of the pump. With the harness installed, I have NO resistance. With the harness disconnected I have infinite resistance.
Correct me if I am wrong, I think all of these test results are telling me I have an electical problem, not a fuel pump issue. I have read threads about the inertia switch and the selector switch as being the possible problem. I cannot locate the inertia switch and do not know if the gray thing under the drivers side (amid ship) is the selector and if it is, how to test or repair/replace it. Any help or suggestions would be GREATLY appreciated as I am becoming desparate.
This is a new thread to the on-going saga of my not being able to start my 91 E150. It is a 5.0L EFI, dual tanks and AT (if the tranny type makes a difference). I started having problems with not being able to start it about a week ago. The engine rotates freely and I have spark, so I began checking the fuel. After trying repeated to start the van on either tank, I replaced the fuel relay and filter. This did not fix the problem.
So I started pulling fuel lines. Since I don't have a pressure gauge, I can only test the lines with my eyes and a glass jar. The lines are all wet, but no real "splurting" of fuel as I would expect with the key on. Even after pulling a line and testing it in my jar, then reconnecting trying to start and pulling it apart again, the line is wet... I think this means I am getting SOME fuel from the tanks, just not enough.
I started with the inlet and return lines to the rail. The line leading into the regulator (is this the inlet side?) was wet and the other (return?) line had more fuel. I pulled the line leading from the inlet of the HP in line pump... same condition at each connection all the way back to the inlet side of the selector switch (I think... thing with four lines leading into and out of). The line was full of fuel, but no real volume. I hear a click at the tanks, but cannot hear any of the pumps engage (although I never could even when it ran fine) and cannot feel the high volume pump trying to operate.
Next, I tested for power at the high volume pump, I found none on either side of the connector. I checked for power at the relay, it tests fine. On a whim, I turned the key off and checked continuity between the positive and negative sides of the pump. With the harness installed, I have NO resistance. With the harness disconnected I have infinite resistance.
Correct me if I am wrong, I think all of these test results are telling me I have an electical problem, not a fuel pump issue. I have read threads about the inertia switch and the selector switch as being the possible problem. I cannot locate the inertia switch and do not know if the gray thing under the drivers side (amid ship) is the selector and if it is, how to test or repair/replace it. Any help or suggestions would be GREATLY appreciated as I am becoming desparate.
More Turbo
Joined: Jun 2004
Posts: 690
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From: Sweden
When you turn the key the high pressure pump and the tank sump pump which is pointed to by the tank switch up front (the tank valve position has nothing to do with it) will turn on for about 2 sec to pressurize the system when the key is turned.
They run continuously once the engine is running. The fuel pressure reg bleeds off the pressure back to the tank by popping open as the pressure exceeds 35-40 psi over the intake manifold pressure. If the tank has been run dry and there is air in the lines, putting in fuel and turning the key a few times will always circulate the air back into the tank and refill the injector rails fine.
When it's not running it will be 35-40 psi. The fuel pressure can be tested by a tire gauge. Of course be extremely careful about spills and sparks and it may ruin the gauge.
If the vac hose from the intake manifold to the regulator has fuel in it, the diaphragm is busted and you need a new one.
The tank selector valve, under the frame near the high pressure pump, is failure-prone and should be suspected.
In my experience the 5.0L dual tank E150 ran just fine with the tank sump disabled! I had the tank valve jammed and it was running off the rear tank with the front fuel pump selected, there was no power at all to the rear tank pump. Ran fine for a long time before I realized that, apparently the high pressure pump has enough draw to suck it out and still maintain proper pressure under flow. Not that you shouldn't make it work but if it won't start I would start looking elsewhere.
They run continuously once the engine is running. The fuel pressure reg bleeds off the pressure back to the tank by popping open as the pressure exceeds 35-40 psi over the intake manifold pressure. If the tank has been run dry and there is air in the lines, putting in fuel and turning the key a few times will always circulate the air back into the tank and refill the injector rails fine.
When it's not running it will be 35-40 psi. The fuel pressure can be tested by a tire gauge. Of course be extremely careful about spills and sparks and it may ruin the gauge.
If the vac hose from the intake manifold to the regulator has fuel in it, the diaphragm is busted and you need a new one.
The tank selector valve, under the frame near the high pressure pump, is failure-prone and should be suspected.
In my experience the 5.0L dual tank E150 ran just fine with the tank sump disabled! I had the tank valve jammed and it was running off the rear tank with the front fuel pump selected, there was no power at all to the rear tank pump. Ran fine for a long time before I realized that, apparently the high pressure pump has enough draw to suck it out and still maintain proper pressure under flow. Not that you shouldn't make it work but if it won't start I would start looking elsewhere.
