Need help: odd fueling issue

BrandonMag

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Monday afternoon I was buttoning up all of the work I had done to the '88 F-250 (I recently posted about installing a 3G alternator and new fuel injectors). I removed the injection pump top cover because I was curious to see inside of it (which was stupid, because I think it led to the issue I am currently having). I reinstalled the top cover, barred the engine over to line the hex fuel screw up with the side cover, removed the side cover, turned the fuel up two flats, reinstalled the side cover, double-checked everything, and fired it up. WHOOPS! I had reinstalled the top cover incorrectly and the engine revved way up. I quickly removed the fuel filter and the engine shut off within 15 seconds. (Whew, close call!) I removed the injection pump top cover, fiddled around, got it lined up correctly and reinstalled it. Cranked it over again and it fired up, this time idling around 900 RPM and sounding fine.
I took it for about a 20 mile drive and as I was on my way home I noticed a slight stumble. The rear fuel tank was being used and the fuel gauge for the rear tank does not work, so I assumed the rear tank was running low on fuel and switched to the front tank. No problem, it seemed to run fine; I stopped by the fuel station to fill both tanks up with diesel. After filling them up with diesel, I cranked the engine and it just spun over. The engine cranked just as it normally does, but it would not actually start and there wasn't any white smoke coming out of the tailpipe (which told me I wasn't getting any fuel). Of course I hadn't brought any tools with me, but the fuel station is only about 1/4 mile from my house, so I walked home, grabbed a couple of tools to bleed air from the Schrader valve on the filter head and walked back to the truck. I installed an electric fuel pump a couple of weeks ago, so I turned it on while holding the Schrader valve open and quite a lot of air came out. Eventually, a steady stream of fuel came out, so I closed the Schrader valve and tried to start it again. Same thing as last time: it would spin just fine, but it would not fire. (Also, there was no white smoke coming from the tailpipe.) Acknowledging defeat, I walked home, grabbed my '89 F-250, asked my wife to give me a hand for a few minutes, and together we towed the '88 F-250 home.
I let it sit yesterday and decided this morning that I would fix it. I have literally removed the injection pump top cover six (maybe seven?) times, and I am pretty sure that I have it lined up correctly. Each time I turn the key on to open the FSS it clicks, but it is sort of a squishy sounding click, not a snap like I would have expected. I think the first (or maybe the second?) time I reassembled the top cover I replaced the black rubber fuel return line with a clear plastic line to see if fuel was actually coming from the injection pump to the fuel return line. It did the first or second time and I tried to start it, but it would just turn over and not start. I've done this several times, there is no fuel coming out of the clear plastic return line and each time the engine will turn over but will not start; there is no smoke coming out of the tailpipe.
I'm at a loss: I have searched around here on OB and looked at three or four different Stanadyne DB2 manuals online to understand the correct interface between the FSS lever in the IP top cover and the lever it engages in the IP main body. I also watched this video:
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Assuming the information in the video is correct, I'm pretty sure the IP top cover is attached to the IP body correctly. On Monday evening, once I had the IP reassembled "correctly" it seemed to run fine (other than the slight stumble previously mentioned) until I got fuel. I can say for sure it is getting fuel to the filter head, but it seems like the injection pump is not getting fuel. Any ideas?
 
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Booyah45828

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Are you cranking it at full throttle? Try that and report back.

Fuel should come out of the housing while cranking. No fuel out the housing tells me it doesn't have fuel or the transfer pump isn't pumping. Remove the timing cover on the side and see if the rotor is turning while you crank. If it is, your pump should be getting/pushing fuel. If it's not, you broke the shaft and need a new pump.
 

BrandonMag

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Fuel should come out of the housing while cranking. No fuel out the housing tells me it doesn't have fuel or the transfer pump isn't pumping. Remove the timing cover on the side and see if the rotor is turning while you crank. If it is, your pump should be getting/pushing fuel. If it's not, you broke the shaft and need a new pump.
I agree that fuel should be coming out of the IP housing when the electric lift pump is pumping. Checking to see if the rotor turns when cranking the engine was a good idea; I pulled the side cover off and had my wife bump the starter. The rotor turned just as it should. I replaced the side cover and then pulled the IP top cover off; I wanted to verify that the now empty IP would fill up with fuel from the electric lift pump... and it did not. I thought that maybe I had sucked up some sludge from the bottom of the rear tank when it was low (clogging the fuel filter), so I removed the fuel line from the filter head to the IP. I turned on the electric lift pump and fuel shot out of the 90* fitting. I turned off the lift pump, reinstalled the fuel line, turned on the lift pump and rechecked the opened IP to see if any fuel was getting into it. It was not. There's what appears to be an extension of sorts between the fuel line fitting on the end of the IP and the IP body itself (pictured). Is this something that could be plugged?
 

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gandalf

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That "extension" looks pretty normal to me. I'll attach a picture of a brand new IP. What you don't see in the picture is the nut which is on the hard line from the fuel filter.
 

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BrandonMag

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That "extension" looks pretty normal to me. I'll attach a picture of a brand new IP.
I thought the same; thanks for the pic.
Since I am 100% sure I am getting fuel through the filter and through the hard line, there is an obstruction between the hard line and the body of the IP. (The electric lift pump I installed is working; I verified that when diesel shot out of the 90* fitting on the fuel filter head.) Does the IP need to be turning for the fuel from the hard line to get into the IP?
 

gandalf

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Yes, I'm almost positive that the IP must be turning for the fuel to get through. If the shaft is broken it will not turn. I'm sure there must be other reasons also.

Another picture. If you undo that "extension where the hard line goes into the IP you will find a screen filter. Its conceivable that screen could be plugged. The picture is taken through a mirror.
 

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Big Bart

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Some thoughts -

1) I would replace the IP soleniod, just take that out of the equation. Fiddling with it seems to let you start the engine but not restart it. You said it had a soft click, guessing it is not moving all the way. If it does not move all the way, it will not start.
2) I would replace the fuel filter since you opened and retightened. It may be allowing air in.
3) You mentioned a new E fuel pump. Is this the main lift pump or to supplement your mechanical pump?
4) Our fuel tank selector valves are getting to that age they are going out. You should confirm your valve is working. If not replace it.
 
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BrandonMag

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Yes, I'm almost positive that the IP must be turning for the fuel to get through. If the shaft is broken it will not turn. I'm sure there must be other reasons also.

Another picture. If you undo that "extension where the hard line goes into the IP you will find a screen filter. Its conceivable that screen could be plugged. The picture is taken through a mirror.
I wonder if the rotor/shaft/plungers/etc. all need to be lined up correctly for fuel to flow through the IP and out of the return line; I may have just gotten lucky this morning when I swapped the black rubber fuel line over to clear and could see just a dribble of fuel passing through.
I removed the extension and using my inspection mirror saw exactly what you pictured. I carefully looked around the screen area with a fairly powerful LED flashlight; I saw no bits of debris or anything else that looked out of the ordinary. (I gently poked around with a pick just to make sure there was nothing in there that should not have been.) I've now reinstalled the hard line. I bumped over the engine a couple of times with the electric lift pump on but I'm not seeing much if any additional fuel in the IP body.
So ***?! Why would an IDI start and run and then after getting fuel at a station not start? The most obvious answer that occurs to me is bad fuel (which would lead to a plugged fuel filter), but I KNOW there is fuel passing through the filter to the IP. I am stumped.
 

BrandonMag

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Some thoughts -

1) I would replace the IP soleniod, just take that out of the equation. Fiddling with it seems to let you start the engine but not restart it. You said it had a soft click, guessing it is not moving all the way. If it does not move all the way, it will not start.
2) I would replace the fuel filter since you opened and retightened. It may be allowing air in.
3) You mentioned a new E fuel pump. Is this the main lift pump or to supplement your mechanical pump?
4) Our fuel tank selector valves are getting to that age they are going out. You should confirm your valve is working. If not replace it.
1) Where can I buy a new FSS?
2) These damn fuel filters are $60 at the local auto stores. Since I'm pretty sure I'm getting air-free fuel (verified several times at the Schrader valve and the hard line between the fuel filter head and IP), I won't be replacing the fuel filter until it's a last option.
3) I bypassed the mechanical lift pump completely. I have only the electric lift pump supplying the IP with fuel.
4) I agree with what you're saying, but it seems to me that because I have switched between both tanks while driving with no issues over the last couple of weeks=the FSV is good.
 

Big Bart

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1) Where can I buy a new FSS?
2) These damn fuel filters are $60 at the local auto stores. Since I'm pretty sure I'm getting air-free fuel (verified several times at the Schrader valve and the hard line between the fuel filter head and IP), I won't be replacing the fuel filter until it's a last option.
3) I bypassed the mechanical lift pump completely. I have only the electric lift pump supplying the IP with fuel.
4) I agree with what you're saying, but it seems to me that because I have switched between both tanks while driving with no issues over the last couple of weeks=the FSV is good.
I am sure the folks on this list can


But Mel has it listed below -

 

Big Bart

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1) Where can I buy a new FSS?
2) These damn fuel filters are $60 at the local auto stores. Since I'm pretty sure I'm getting air-free fuel (verified several times at the Schrader valve and the hard line between the fuel filter head and IP), I won't be replacing the fuel filter until it's a last option.
3) I bypassed the mechanical lift pump completely. I have only the electric lift pump supplying the IP with fuel.
4) I agree with what you're saying, but it seems to me that because I have switched between both tanks while driving with no issues over the last couple of weeks=the FSV is good.
My guess it is the FSS.

Hear You on the filter.

Just FYI any pump that pumps more than 8psi at the filter head might be causing running issues. But you said when it runs it runs good. So guessing not an issue here.

Just keep the valve in mind if a new FSS does not fix the issue.
 

BrandonMag

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Thanks for all the responses; it sure is frustrating to have what should be a simple issue to fix. I had just about given up on it for the evening and thought, "What the hell, I'll try to start it one more time." I cranked on it for about 15 seconds and it started! :cool:
Of course, if this issue pops up again I'll repost here. (Hopefully it does not.)
 

IDIDIDIhoDhoDhoDO

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So now that it works again is the fuel shutoff solenoid sounding any different? A fast click or still a squishy click? I suspect a failing FSS like Bart does. If the problem recurs I'd test it. Test the resistance from the terminal to ground with the IP cap still on, the take the cap off and see if the solenoid plunger moves freely or not.
 

Booyah45828

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I thought the same; thanks for the pic.
Since I am 100% sure I am getting fuel through the filter and through the hard line, there is an obstruction between the hard line and the body of the IP. (The electric lift pump I installed is working; I verified that when diesel shot out of the 90* fitting on the fuel filter head.) Does the IP need to be turning for the fuel from the hard line to get into the IP?
Yes,

There is a vane style transfer pump that needs to be turning in order to let fuel into the pump. Usually, if the rotor is turning, so is the transfer pump, which is why I asked if the rotor was turning. The transfer pump will provide fuel to the calibrated air bleed which will fill the housing with fuel, regardless of metering valve position.

Sounds to me you just had air in the pump. Can be hard to get out, which is why I recommend cranking with it floored, as that gives it full fuel, which helps to bleed the pump/lines/injectors.
 
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BrandonMag

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So now that it works again is the fuel shutoff solenoid sounding any different? A fast click or still a squishy click? I suspect a failing FSS like Bart does. If the problem recurs I'd test it. Test the resistance from the terminal to ground with the IP cap still on, the take the cap off and see if the solenoid plunger moves freely or not.
It sounds pretty much the same as it did: it clicks, but you can also hear what I assume is the spring return inside of the injection pump.
I appreciate the advice but I think the FSS is okay; I've started it about five times since my last post and it works great. I think Booyah45828 hit the nail on the head: air in the fuel lines.
 
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