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I took willie to the motor vehicle inspection station this morning. On the way, curiously after it got up to temp, it started bucking and jerking when I gave it
throttle. I limped it to the shop.
I SUSPECT it's the EGR acting up. guessing at this point. will run the codes if any when I get it back from them later this afternoon.
Does anyone (numberdummy?) know the correct part number from Ford or Motorcraft for the EGR valve?
I doubt it's an egr problem. EGR problems usually show them selves at idle, not at part throttle.
I would look at your ignition system, coil, rectangular connector on the coil, and check your fuel pressure. If you describe the problem with more details, truck year, like when it's bucking, we might be able to narrow it down further.
the idle was a bit rough when I first took it out of the garage from winter storage. I cleaned the IAC valve thoroughly and that seemed to make it
idle smooth. Was not until I took it out on the highway and it got up to temp that I started noticing the bucking/jerking behaviour when attempting
to accelerate. truck info is in my post. has 122K miles. Tuneup (plugs, rotor button, cap, coil) done in 2023. very few miles put on it since then.
When my front tank fuel pump was failing, and my fuel tank selector valve was full of corrosion, my truck would idle, or drive around the yard all day. I had to drive it at 55 to 60 mph for 6 or 7 miles before it would start bucking and jerking.
In my case, if I switched to the rear tank, the problem resolved.
As already stated, I would check fuel pressure while driving.
Since my truck was a project, and hadn't been started or driven regularly in the previous five years, I started by investigating the Dual Function Reservoir. It was full of corrosion. I replaced it. Twenty four hours later, I had the same problem. I replaced the front tank fuel pump with a Delphi. It's been ok for 18 months. The 5 year old Dual Function Reservoir I replaced in 2023.
one of the first things I replaced was the dual fuel reservoir (used a NOS ford OEM one). I have been running mainly on the front tank for
the past 2 years. I'll try switching over to the rear tank and see how that changes behaviour (if any).
one of the first things I replaced was the dual fuel reservoir (used a NOS ford OEM one). I have been running mainly on the front tank for
the past 2 years. I'll try switching over to the rear tank and see how that changes behaviour (if any).
I methodically alternate fuel tanks. I switch once a day. That's just me. I figure fuel sits on top of that metal disc for extended periods of time, if I don't alternate tanks.
Is the fuel in your rear tank two years old? That might not be good.
no, the front tank is pretty near empty. I have been using the rear tank pretty much exclusively as the front sending unit
for level is wonky. But the truck runs on both tanks. I switched to the front tank on the way home. same behaviour is
exhibited.
Just finished testing the EVP and EVR solenoid units. They are working as should. EVR produces good vacuum to
the EGR valve when engine is at temp and the engine is revved up. I'm seeing near 20 inch of vacuum when I do this.
Let off on the throttle and the vacuum returns back to 0.
Checked the EVP solenoid and it the plug is receiving 4.5V DC on the 2 pins used for testing. On the valve, I see
almost 4000 Ohms of resistance which I believe is in spec. Just took the valve off to inspect it. It is filled with black
soot buildup. Using carb spray to clean it out. The pintle valve can be opened with mild pressure...so it ain't frozen
and when you release pressure it returns to the closed position. Whether it hold a vacuum...next test to be done.
gonna have to bite the bullet and buy a fuel pressure test kit. been putting it off....
you were right...the EGR is working as it should...there was some carbon buildup on the tube and inside the valve but
nothing that prevented it from working. cleaned it out good. valve holds a vacuum and it gets a vacuum from the EVR
on throttle when the engine is warmed up.
will post again when I have test results from doing a fuel pressure test.
gonna have to bite the bullet and buy a fuel pressure test kit. been putting it off....
you were right...the EGR is working as it should...there was some carbon buildup on the tube and inside the valve but
nothing that prevented it from working. cleaned it out good. valve holds a vacuum and it gets a vacuum from the EVR
on throttle when the engine is warmed up.
will post again when I have test results from doing a fuel pressure test.
thx to all for chiming in.
You can borrow fuel pressure testers from your local big auto parts stores for free. Just make sure they include the Schrader adapter.
I obtained (loaner) an OEM tools fuel pressure test kit. Hooked it up the schraeder valve on the fuel rail. (key off). Nothing registered on
the guage. I noticed a bit of fuel coming out of connection when I was securing it so it must be depressing the nipple in the valve.
Then turned key to the RUN position and got nothing on the guage....zero. Meaning either there is no power being supplied to the
high pressure pump or there is power but it is not activating.
I put the jumper wire per how-to thread on performing this test on the EEC-IV connector (bottom right blade connector) and grounded
it out. About to check the hot wire on the pump to see if 12V are registered. I'm assuming I should hear an audible hum from the pump
when it activates?
I am seeing 12V solid on the hot wire (light colored one) on the pump with the jumper on the EEC-IV test connector and key in the RUN
position. Pump is not coming on. So it would appear the pump has STB. I did notice in the engine bay that there was a bit of smoke coming
from the relay blocks just in front of the brake booster. I'm assuming these are the fuel pump relay and another one. One is green the other
is cream colored. I believe the green one is for the fuel pump. correct me if I'm wrong.
This would be too much draw being made trying to get the high pressure fuel pump to come on?
Which high pressure fuel pump is recommended for replacement here? I'm thinking the Delphi FD0029 or the Bosch 69100.
I don't know about this. You shouldn't have any smoke in your engine compartment. And it's odd your fuel pump took a dump right as you were testing it.
There is a common problem with loaner fuel pressure tester. The schrader valve plunger isn't long enough to depress the valve core, so the gauge never gets to see the pressure. It's easy to remove the valve core and repeat the test. You can also try to measure the fuel pump amp draw. It should be about 5 amps. See this photo to test it with multimeter.
Carter, spectre and Delphi are the favored fuel pump flavors around here.
I don't know about this. You shouldn't have any smoke in your engine compartment. And it's odd your fuel pump took a dump right as you were testing it.
There is a common problem with loaner fuel pressure tester. The schrader valve plunger isn't long enough to depress the valve core, so the gauge never gets to see the pressure. It's easy to remove the valve core and repeat the test. You can also try to measure the fuel pump amp draw. It should be about 5 amps. See this photo to test it with multimeter.
Carter, spectre and Delphi are the favored fuel pump flavors around here.
I did suspect that the fuel pressure test kit was a problem...so I disconnected it from the schraeder valve and put it on the truck front tire and the guage showed the pressure of the tire just fine.
Other than the fuel pump being sezed up and it drawing a huge amperage amount, why would the fuel pump relay start to smoke?
Also, to test the amerage draw, my truck (87 model year) just has the fuel relay block I believe...no "normal" blade style fuse. to get at the pins to do the amp draw test as you
show above, you would have to separate the block from the engine wire harness which would render it inoperable....would I just go in from the rear of the block with it connected
to the proper pins to do this test? If so what color wires need to be tested?
Is it POSSIBLE that the truck would run (crappy or at all) with only the in-tank pump working?
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