Will your IDI do 70mph?
Thread Starter
|
Trailering
Joined: Aug 2019
Posts: 18
Likes: 0
Thanks for all the responses. This working out of town business really limits my wrench turning time, but
I was able to fiddle around some more on the truck when I got back into town this afternoon. I checked the fuel pressure at the filter and saw 3psi at idle. I think this is low, but it didn't decrease when I revved the engine. I was not able to position the gauge in a way that would allow me to see it while I was driving, so I don't know if the fuel pressure holds steady while going down the road.
For some reason, whoever wired the fuel pump wired it directly into the fuel shutoff solenoid circuit. If I have time this weekend, I will rewire it with a relay and see what happens.
I was able to fiddle around some more on the truck when I got back into town this afternoon. I checked the fuel pressure at the filter and saw 3psi at idle. I think this is low, but it didn't decrease when I revved the engine. I was not able to position the gauge in a way that would allow me to see it while I was driving, so I don't know if the fuel pressure holds steady while going down the road.
For some reason, whoever wired the fuel pump wired it directly into the fuel shutoff solenoid circuit. If I have time this weekend, I will rewire it with a relay and see what happens.
Fleet Mechanic
Joined: Jul 2010
Posts: 1,753
Likes: 34
From: Los Angeles, Ca.
And in answer to your original question; my previous '88 and current '91 both do 70 comfortably, but they take a while to get there. The '88 had a C-6 and 3.5ish gears (3.54?), and weighed 8800 I think. The '91 has a E4OD and 4.11, has a raised roof (ambulance) and probably weighs about the same. Both have gone over 80 but I generally don't pass 75, 70 is most common.
i ain't rite
Joined: Mar 2005
Posts: 65,450
Likes: 5,520
From: Marlboro Mental Hospital.
Thanks for all the responses. This working out of town business really limits my wrench turning time, but
I was able to fiddle around some more on the truck when I got back into town this afternoon. I checked the fuel pressure at the filter and saw 3psi at idle. I think this is low, but it didn't decrease when I revved the engine. I was not able to position the gauge in a way that would allow me to see it while I was driving, so I don't know if the fuel pressure holds steady while going down the road.
For some reason, whoever wired the fuel pump wired it directly into the fuel shutoff solenoid circuit. If I have time this weekend, I will rewire it with a relay and see what happens.
I was able to fiddle around some more on the truck when I got back into town this afternoon. I checked the fuel pressure at the filter and saw 3psi at idle. I think this is low, but it didn't decrease when I revved the engine. I was not able to position the gauge in a way that would allow me to see it while I was driving, so I don't know if the fuel pressure holds steady while going down the road.
For some reason, whoever wired the fuel pump wired it directly into the fuel shutoff solenoid circuit. If I have time this weekend, I will rewire it with a relay and see what happens.
what brand electric pump is on it? my bet is a cheay mr gasket style gas e-pump.
you need a diesel rated pump, like the facet duralift 40285.
a lot of people have switched to the 40222.
best place i found for facet pumps is aircraftspruce.
https://www.aircraftspruce.com/catalog/eppa
Fleet Mechanic
Joined: Jul 2010
Posts: 1,753
Likes: 34
From: Los Angeles, Ca.
me thinks you found your problem. 3 psi at idle is way too low. should be closer to 7-8 at idle.
what brand electric pump is on it? my bet is a cheay mr gasket style gas e-pump.
you need a diesel rated pump, like the facet duralift 40285.
a lot of people have switched to the 40222.
best place i found for facet pumps is aircraftspruce.
https://www.aircraftspruce.com/catalog/eppa
what brand electric pump is on it? my bet is a cheay mr gasket style gas e-pump.
you need a diesel rated pump, like the facet duralift 40285.
a lot of people have switched to the 40222.
best place i found for facet pumps is aircraftspruce.
https://www.aircraftspruce.com/catalog/eppa
i ain't rite
Joined: Mar 2005
Posts: 65,450
Likes: 5,520
From: Marlboro Mental Hospital.
All of the Facet pumps are diesel rated. When I was pump shopping for a generator I was shocked to find that an aircraft place had the best price on it, and delivery was fast. If the pump is mounted down near the frame one of the cheaper ones should be fine, but high up in the engine compartment the duralift might be necessary. I don't know why some people mount them in the engine compartment, seems like the worst place for it, but for some reason this is popular with IDI people.
Mountain Pass
Joined: Apr 2021
Posts: 144
Likes: 16
From: Fratt, TX
And in answer to your original question; my previous '88 and current '91 both do 70 comfortably, but they take a while to get there. The '88 had a C-6 and 3.5ish gears (3.54?), and weighed 8800 I think. The '91 has a E4OD and 4.11, has a raised roof (ambulance) and probably weighs about the same. Both have gone over 80 but I generally don't pass 75, 70 is most common.
New User
Joined: Jul 2020
Posts: 15
Likes: 1
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Senior User
Joined: Mar 2014
Posts: 434
Likes: 2
From: Santa Cruz Mountains
Do you have to be driving it down the road to see what the psi is at higher rpms?
isnt it the same to throttle it at the injection pump right at the engine?
Maybe the engine bay is the best because of the wiring. That’s the only place i have found the on/off power.
isnt it the same to throttle it at the injection pump right at the engine?
Maybe the engine bay is the best because of the wiring. That’s the only place i have found the on/off power.
i ain't rite
Joined: Mar 2005
Posts: 65,450
Likes: 5,520
From: Marlboro Mental Hospital.
i have my E-pump wired into the cab to a hidden toggle switch, which is powered by a fused power source in the fuse box.
if i remember correctly, it is hooked to the power window fuse.
if i remember correctly, it is hooked to the power window fuse.
Thread Starter
|
Trailering
Joined: Aug 2019
Posts: 18
Likes: 0
me thinks you found your problem. 3 psi at idle is way too low. should be closer to 7-8 at idle.
what brand electric pump is on it? my bet is a cheay mr gasket style gas e-pump.
you need a diesel rated pump, like the facet duralift 40285.
a lot of people have switched to the 40222.
best place i found for facet pumps is aircraftspruce.
https://www.aircraftspruce.com/catalog/eppa
what brand electric pump is on it? my bet is a cheay mr gasket style gas e-pump.
you need a diesel rated pump, like the facet duralift 40285.
a lot of people have switched to the 40222.
best place i found for facet pumps is aircraftspruce.
https://www.aircraftspruce.com/catalog/eppa
I'm just going to order another pump spec'd at the correct pressure and bypass the mechanical pump all together.
I have attached a picture of the fuel pump as well as a picture of the truck.
Thread Starter
|
Trailering
Joined: Aug 2019
Posts: 18
Likes: 0
Fleet Mechanic
Joined: Jul 2010
Posts: 1,753
Likes: 34
From: Los Angeles, Ca.
If you just hold higher RPM in neutral it's not going to be much of a test. Doing a hard rev from idle might show something. If it were an automatic you could power brake it to also see what it does under load.
It's possible that the electric pump has failed and become a restriction.
It's possible that the electric pump has failed and become a restriction.
Senior User
Joined: Mar 2014
Posts: 434
Likes: 2
From: Santa Cruz Mountains
Is the way to go on the electric fuel pump mod to leave the manual attached/installed or bypass/remove?
my 90 came with the cheap green one and feeds the manual. Only need it under heavy loads when the engine starts running out of fuel.
What causes this? Certainly the factory didnt sell these trucks with this limitation
my 90 came with the cheap green one and feeds the manual. Only need it under heavy loads when the engine starts running out of fuel.
What causes this? Certainly the factory didnt sell these trucks with this limitation