Efi Pump Pressure Drops
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From: BAYVILLE
Efi Pump Pressure Drops
my 1990 ford 5.0 302 e150 van efi pump pressure drops when key is on
this model has two pumps one is the external and other is in tank
so i don.t know if both are bad how can i test to see if witch one
is bad i know i tested the pump pressure maybe a yearago it was i belive
it was 40 psi
this model has two pumps one is the external and other is in tank
so i don.t know if both are bad how can i test to see if witch one
is bad i know i tested the pump pressure maybe a yearago it was i belive
it was 40 psi
Fleet Owner
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From: Easton,Ks
You would need to put a gauge on the fuel manifold and then with the key on with a cold engine not running ground pin #6 of the DLC (test connector).
It should read about 42 PSI, remove the ground and it should hold for a little while and then drop very slowly and be down to zero by about 6 hours. But should not drop below 35 PSI for at least a half-hour.
If the fuel pressure drops off as soon as you remove the ground then you have a bad check valve in the Hi-Pressure pump on the frame or a bad fuel pressure regulator.
Also take the vacuum hose off the fuel pressure regulator while pin#6 is grounded and see if fuel comes out of the nipple the hose was on. If it does you have a bad fuel pressure regulator.
It should read about 42 PSI, remove the ground and it should hold for a little while and then drop very slowly and be down to zero by about 6 hours. But should not drop below 35 PSI for at least a half-hour.
If the fuel pressure drops off as soon as you remove the ground then you have a bad check valve in the Hi-Pressure pump on the frame or a bad fuel pressure regulator.
Also take the vacuum hose off the fuel pressure regulator while pin#6 is grounded and see if fuel comes out of the nipple the hose was on. If it does you have a bad fuel pressure regulator.
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Geez, just how different were the fuel systems between 86 and 90?
Because if similiar rules apply, I can't rightfully dismiss fuel pressure as a potential factor to my problems, recalling with a fair degree of certainty, we never performed such tests.
Its probably best I take mine into a shop this week, for a more thorough and accurate accounting on the current state, of a once again suspect fuel rate.
Because if similiar rules apply, I can't rightfully dismiss fuel pressure as a potential factor to my problems, recalling with a fair degree of certainty, we never performed such tests.
Its probably best I take mine into a shop this week, for a more thorough and accurate accounting on the current state, of a once again suspect fuel rate.
Last edited by van_a_knockin; Jul 9, 2007 at 01:48 AM.
Fleet Owner
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From: Easton,Ks
Originally Posted by van_a_knockin
Geez, just how different were the fuel systems between 86 and 90?
The difference in the two fuel systems was in the Reservoir and the fuel selector valve.
The 85-87 E-series FI had the Type 3 fuel system and the 88-90 had the Type 4 fuel system if they had two fuel tanks.
In 1991 the E-series vans went to just in-tank pumps without the selector valve or Reservoir and moved the check valve inside the tank and added a shuttle valve in the tank also for the return fuel. This was the same fuel system as the F-series Trucks had starting in 1990.
Here is a diagram of the Type #4 fuel system and I posted a diagram of your Type #3 fuel system over in your Thread.
https://www.ford-trucks.com/forums/6...ual-tanks.html
Last edited by subford; Jul 9, 2007 at 06:37 AM.
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From: Waterford, Mi.
Subford,,,
I'm having the same problem with my 89 E150 (5.0, dual tanks)..
I was reading in my haynes manual, and it says to "completely pinch off the return line downstream of the regulator",, and then observe the fuel pressure leakage rate... It then says "if the leakage slows significantly, replace the regulator"... They say to pinch off a rubber section of the line with a c-clamp.... But there is no rubber section,, it appears to be all plastic line with a rubber sheath over it...
Is it really a good idea to clamp down on an 18 year old plastic fuel line?
I'm having the same problem with my 89 E150 (5.0, dual tanks)..
I was reading in my haynes manual, and it says to "completely pinch off the return line downstream of the regulator",, and then observe the fuel pressure leakage rate... It then says "if the leakage slows significantly, replace the regulator"... They say to pinch off a rubber section of the line with a c-clamp.... But there is no rubber section,, it appears to be all plastic line with a rubber sheath over it...
Is it really a good idea to clamp down on an 18 year old plastic fuel line?
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Originally Posted by rog_j
Subford,,,
I'm having the same problem with my 89 E150 (5.0, dual tanks)..
I was reading in my haynes manual, and it says to "completely pinch off the return line downstream of the regulator",, and then observe the fuel pressure leakage rate... It then says "if the leakage slows significantly, replace the regulator"... They say to pinch off a rubber section of the line with a c-clamp.... But there is no rubber section,, it appears to be all plastic line with a rubber sheath over it...
Is it really a good idea to clamp down on an 18 year old plastic fuel line?
I'm having the same problem with my 89 E150 (5.0, dual tanks)..
I was reading in my haynes manual, and it says to "completely pinch off the return line downstream of the regulator",, and then observe the fuel pressure leakage rate... It then says "if the leakage slows significantly, replace the regulator"... They say to pinch off a rubber section of the line with a c-clamp.... But there is no rubber section,, it appears to be all plastic line with a rubber sheath over it...
Is it really a good idea to clamp down on an 18 year old plastic fuel line?
I do not think there was ever a big problem with the Fuel Pressure regulator not holding pressure. The big problem with fuel pressure regulators is the diaphragm leaking gas into the intake though the vacuum nipple on top of it.
In 1993 they had problems with the regulators not opening and blowing the check valves.
If your pressure drops fast after you turn off the key you probably have a bad check valve in your hi-pressure fuel pump on the frame.
Here is a diagram of the regulator:
Last edited by subford; Jul 23, 2007 at 08:20 PM.
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From: Waterford, Mi.
Thanks for the reply..
As for the pressure leakage on my 89,, it only takes about 15 seconds for the pressure to drop from about 40psi to almost zero. And cold starts have been getting continually worse. I'll spring for a new pump and be sure to let you know how it works out..
The idle on this van seems to do whatever the heck it feels like doing when it's cold too (racing up and down)... Maybe a dumb question, but do you think it's related to the fuel pressure problem. I've replaced the IAC valve, TPS, and vacuum is solid at 20in. at idle.
Obviously I'm new to the whole EFI thing.
As for the pressure leakage on my 89,, it only takes about 15 seconds for the pressure to drop from about 40psi to almost zero. And cold starts have been getting continually worse. I'll spring for a new pump and be sure to let you know how it works out..
The idle on this van seems to do whatever the heck it feels like doing when it's cold too (racing up and down)... Maybe a dumb question, but do you think it's related to the fuel pressure problem. I've replaced the IAC valve, TPS, and vacuum is solid at 20in. at idle.
Obviously I'm new to the whole EFI thing.
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Fleet Owner
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From: Easton,Ks
You may have an injector problem leaking the fuel down. Do you get black smoke when you start it?
If not:
Also try turning the key off and on about four times before you start it and if it stars right up with no smoke then I would say the HP pump check valve.
Also it is not 100% certain that it is not the fuel pressure regulator as it could have a bad seat. But if you get 42 PSI fuel pressure with engine off and about 33 PSI WOT and it does not leak fuel into the vacuum system then it more than likely good.
If not:
Also try turning the key off and on about four times before you start it and if it stars right up with no smoke then I would say the HP pump check valve.
Also it is not 100% certain that it is not the fuel pressure regulator as it could have a bad seat. But if you get 42 PSI fuel pressure with engine off and about 33 PSI WOT and it does not leak fuel into the vacuum system then it more than likely good.
Last edited by subford; Jul 23, 2007 at 08:13 PM.
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From: Waterford, Mi.
Nope,, no smoke when it starts,, and doesn't smell or act like it's running rich. I changed the plugs about 2 weeks ago, and they looked fine... Also, even though I didn't see any fuel in the vacuum line from the regulator, I've had my "mightyvac" hooked up to it, and the vacuum held steady when I pumped it up.
I'll try what you mentioned as to the "key off and on" suggestion.
I'll try what you mentioned as to the "key off and on" suggestion.
