Air intrusion problems?
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From: Nelson
Air intrusion problems?
1988 f350 190,000kms.
This is my first diesel truck and I've been trying to address a hard starting issue. I had fuel leaking from my injector return caps, so I got the kit and replaced the o-rings, caps and return lines. But I am still experiencing hard starting. She turns over 10-15 seconds (or more) with no smoke, then two puffs of white, then one black and starts but idles rough for 15-20 seconds. Then runs fine. I'm looking for advice on where to check next for air intrusion or information on what else could be the issue.
This is my first diesel truck and I've been trying to address a hard starting issue. I had fuel leaking from my injector return caps, so I got the kit and replaced the o-rings, caps and return lines. But I am still experiencing hard starting. She turns over 10-15 seconds (or more) with no smoke, then two puffs of white, then one black and starts but idles rough for 15-20 seconds. Then runs fine. I'm looking for advice on where to check next for air intrusion or information on what else could be the issue.
Postmaster
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Make sure all your glow plugs are working.
Look for fuel leaks before the IP, in the supply side of things.
Also, might be worth pulling the return line off the fuel filter and running it into a bucket. Make sure you aren't getting any bubbles coming out while running.
Look for fuel leaks before the IP, in the supply side of things.
Also, might be worth pulling the return line off the fuel filter and running it into a bucket. Make sure you aren't getting any bubbles coming out while running.
i ain't rite
Joined: Mar 2005
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From: Marlboro Mental Hospital.
welcome to FTE.
before trying to start the cold engine remove the fuel filter and see if it is full, or partly empty. if it is full, you are not having air intrusion problems.
as macrob said, i believe you are experience glow plug issues. you probably have 1 or 2 bad glow plugs.
before trying to start the cold engine remove the fuel filter and see if it is full, or partly empty. if it is full, you are not having air intrusion problems.
as macrob said, i believe you are experience glow plug issues. you probably have 1 or 2 bad glow plugs.
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From: Nelson
Thanks for getting back to me. I did replace my glow plugs with a set of motorcraft plugs recently. Then I used a test light at the bullet connectors to check for power getting to the glow plugs, and there was. Is it possible that there is not enough power getting to the glow plugs through the old harness? I have a gp controller bypass and am wary to run the plugs longer than 10 seconds.
Postmaster
Joined: Dec 2011
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First check that each glow plug still works. Not hard - a piece of wire from B+ should spark when touching the terminal on top of the GP. If it doesn't, it's dead.
BTW, if you intend to keep a manual GP system, what I have found to be the best combination is:
1. 6.9-style glow plugs(spade terminal on top) - use Beru, DieselRX or whoever you want that is not Autolite.
2. 7.3 relay and resistor(i.e. the spring-looking piece of metal going from the relay to where the main wire connects).
This makes for a much longer glowing system, in the range of 15 seconds, but also makes it far harder to accidentally fry a glow plug by holding the button too long.
If you want to be extra fancy, you can do as I did and run a 9th glow plug off the relay and into the cab, so you have a visual indication of how hot they are.
BTW, if you intend to keep a manual GP system, what I have found to be the best combination is:
1. 6.9-style glow plugs(spade terminal on top) - use Beru, DieselRX or whoever you want that is not Autolite.
2. 7.3 relay and resistor(i.e. the spring-looking piece of metal going from the relay to where the main wire connects).
This makes for a much longer glowing system, in the range of 15 seconds, but also makes it far harder to accidentally fry a glow plug by holding the button too long.
If you want to be extra fancy, you can do as I did and run a 9th glow plug off the relay and into the cab, so you have a visual indication of how hot they are.
Cross-Country
Joined: Dec 2011
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air intrusion
I have a 86 with 6.9 and had the same problem. If it sets for 1 or 2 days, no problem, the longer it sets the harder to start. The problem was the throttle shaft that goes in one side of pump and out the other side, it had a small leak. The diesel pump repair said they can repair the leak on the truck for $100. I took the pump off and told the to rebuild it complete with a metal governor plate instead of bakelite, it cost $500. I'm hope you know that the original water seperators sucked in air.
nick c
nick c
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I have a 86 with 6.9 and had the same problem. If it sets for 1 or 2 days, no problem, the longer it sets the harder to start. The problem was the throttle shaft that goes in one side of pump and out the other side, it had a small leak. The diesel pump repair said they can repair the leak on the truck for $100. I took the pump off and told the to rebuild it complete with a metal governor plate instead of bakelite, it cost $500. I'm hope you know that the original water seperators sucked in air.
nick c
nick c
One, leaks from the housing of the IP(like the throttle shaft area) are /after/ the IP fueling area. This could be totally empty and it should not affect starting one bit. It might make the system a little more advanced until it fills up(just like with the cold advance on), but I suspect that that leak was /not/ your issue.
Two, you can get a re-seal kit for an IP for about $32, and replace any or all of them yourself with a few hand tools. Done it a couple of times on a good IP with just a seal or two weeping. It went back together just fine.
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I had a similar problem with my truck. Turned out that the diaphragm inside the fuel pump had gone bad and was allowing fuel to drain back. New napa fuel pump and an hour later it was fixed. Havent had any problems since. Another thing it could be is there is a check valve on the side of the fuel filter mount. Looks just like a valve stem for a tire. My boss had a problem on one of his trucks where that went bad and fuel was draining back making it hard to start. A quick way to test that is get a valve cap for a tractor witht eh little rubber seal inside and screw it on. That will create a vaccume and not let fuel drain back. THAT IS NOT THE SOLUTION TO THE PROBLEM Although it can help you diagnose it you would still have to get a new core for the check valve.
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From: Nelson
TJC and Macrobb you were both correct. This was not an issue of air intrusion but simply of not keeping my GPs on long enough. I had heard people talk of burning the GPs out and them swelling so I was overly cautious to a fault. Before I would only do 10 seconds with the GPs. But this morning after the truck sat for 36 hours I did 10 seconds then waited a bit and then nearly another 10 seconds and she started right away. So now my question is; is this a normal amount of time to keep your GPs on? Because they are brand new motorcraft plugs and it has only been getting down to about 10C or 50F at night where I am.
Thanks.
Thanks.
i ain't rite
Joined: Mar 2005
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From: Marlboro Mental Hospital.
down to around 60 degrees or so my truck will WTS light for around 10 seconds. 60 to 30 it will WTS for 12-13 seconds. below 30 is 15 to 20 seconds.
but i have a stock working glow plug controller.
15 seconds will not hurt anything.
my 02 will keep the glow plugs powered for 2 minutes before turning the relay off.
but i have a stock working glow plug controller.
15 seconds will not hurt anything.
my 02 will keep the glow plugs powered for 2 minutes before turning the relay off.
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