TheBirdman
Registered User
7.3 idi Strarting issues/Stuck injector nozzle
A few weeks ago, I inherited my grandpa's old farm truck, and 87 F250 XLT Lariat with a 7.3 idi. The truck has over 500k miles, but the remanufactured engine and trans were put in in 2005 and only have around 90k on them. I replaced the vacuum pump, bought some new tires, put fresh gas in the tanks, and drove 1000 miles home the next day. After that I changed the oil, put a PSD oil filter on, new fuel filter, air filter, flushed coolant and added DCA, replaced the glow plugs with motorcraft ones and glow plug connectors. While starting the truck 3 or 4 times to flush the coolant, I noticed it was getting harder and harder to start. I took it for a test drive and killed it starting off (just about used to the stick shift), and the thing wouldnt start, so I had to leave it overnight and come back. When I came back the next day I replaced the batteries and bled it, but it still wouldnt start, so as a last resort (I know how dangerous it is), I disconnected the glow plugs and started it on a burp of ether and drove it home.
I troubleshooted all that I could think of, and eventually settled on replacing the lift pump, since my gague was reading 0 psi while cranking. The new pump also read 0 psi cranking, but after eventually getting it started, it rose to 3-5 psi. After that it seemed to start reliably, until 2 days ago, when it wouldnt start after turning it off for 5 minutes at the gas station after running for around 2 hours. It is worth noting, an hour or two earlier, it started chugging and cutting out while driving, mainly after starting off from stoplights, but it cleared up after I switched to the front tank. Both tanks were around 75%, so it shouldnt have been the fuel pickup. I grabbed my chain and got someone to pull me down the highway headed for home, and popped the clutch in 3rd, and it started up. It wouldnt idle, and ran really rough for a few minutes, but after that, it worked fine and I drove it home. Yesterday it started fine after sitting for 3 hours without the block heater, and started up in the morning with the block heater.
Because it started fine now, I assumed it just gelled up a little at the gas station. It was around -5, but I had 70% #1, and plenty of additive in the tanks, so it should have been fine. So I figured it was going to work this time, but again it refused to start after being in a meeting for an hour and a half. This time I had my brother bring the old explorer down and I popped the clutch in the parking lot to start it, only this time it didnt run rough at all, it ran like a dream instantly. I dont know why its having trouble starting while cranking, it cranks at at least 500rpm. Also, its cold as hell out here in the winter, so I cant completely rule out gelling. If it was getting slightly gelled enough to not start, would I be able to see the wax in the fuel filter? Another thing to note is back when I was troubleshooting it the second time, I sprayed some electric contact cleaned on the injectors to clean off the fuel from bleeding it while it was idling, and I noticed some bubbling around the BASE of a few of the injectors, where it goes into the head (NOT AT THE INJECTOR CAPS, AT THE BASE). Is it possible the copper crush washers under the injectors are leaking pressure?
Also, my return line/injector cap kit arrived today, so if it will start, Im gonna put the truck in the garage and replace those, and stick a clear hose from the return lines to the filter to see if there are any bubbles while running. Is there anything else I should look for? Anyone got an idea why my truck is PMSing?
A few weeks ago, I inherited my grandpa's old farm truck, and 87 F250 XLT Lariat with a 7.3 idi. The truck has over 500k miles, but the remanufactured engine and trans were put in in 2005 and only have around 90k on them. I replaced the vacuum pump, bought some new tires, put fresh gas in the tanks, and drove 1000 miles home the next day. After that I changed the oil, put a PSD oil filter on, new fuel filter, air filter, flushed coolant and added DCA, replaced the glow plugs with motorcraft ones and glow plug connectors. While starting the truck 3 or 4 times to flush the coolant, I noticed it was getting harder and harder to start. I took it for a test drive and killed it starting off (just about used to the stick shift), and the thing wouldnt start, so I had to leave it overnight and come back. When I came back the next day I replaced the batteries and bled it, but it still wouldnt start, so as a last resort (I know how dangerous it is), I disconnected the glow plugs and started it on a burp of ether and drove it home.
I troubleshooted all that I could think of, and eventually settled on replacing the lift pump, since my gague was reading 0 psi while cranking. The new pump also read 0 psi cranking, but after eventually getting it started, it rose to 3-5 psi. After that it seemed to start reliably, until 2 days ago, when it wouldnt start after turning it off for 5 minutes at the gas station after running for around 2 hours. It is worth noting, an hour or two earlier, it started chugging and cutting out while driving, mainly after starting off from stoplights, but it cleared up after I switched to the front tank. Both tanks were around 75%, so it shouldnt have been the fuel pickup. I grabbed my chain and got someone to pull me down the highway headed for home, and popped the clutch in 3rd, and it started up. It wouldnt idle, and ran really rough for a few minutes, but after that, it worked fine and I drove it home. Yesterday it started fine after sitting for 3 hours without the block heater, and started up in the morning with the block heater.
Because it started fine now, I assumed it just gelled up a little at the gas station. It was around -5, but I had 70% #1, and plenty of additive in the tanks, so it should have been fine. So I figured it was going to work this time, but again it refused to start after being in a meeting for an hour and a half. This time I had my brother bring the old explorer down and I popped the clutch in the parking lot to start it, only this time it didnt run rough at all, it ran like a dream instantly. I dont know why its having trouble starting while cranking, it cranks at at least 500rpm. Also, its cold as hell out here in the winter, so I cant completely rule out gelling. If it was getting slightly gelled enough to not start, would I be able to see the wax in the fuel filter? Another thing to note is back when I was troubleshooting it the second time, I sprayed some electric contact cleaned on the injectors to clean off the fuel from bleeding it while it was idling, and I noticed some bubbling around the BASE of a few of the injectors, where it goes into the head (NOT AT THE INJECTOR CAPS, AT THE BASE). Is it possible the copper crush washers under the injectors are leaking pressure?
Also, my return line/injector cap kit arrived today, so if it will start, Im gonna put the truck in the garage and replace those, and stick a clear hose from the return lines to the filter to see if there are any bubbles while running. Is there anything else I should look for? Anyone got an idea why my truck is PMSing?
Last edited:
