4.9 Starting Issues
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Fleet Mechanic
Joined: Nov 2011
Posts: 1,823
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From: New York
4.9 Starting Issues
Unrelated to the starter engagement issue I've had (separate thread), I'm also experiencing a tough starting problem, especially when cold. Often a long or a couple cranks will be required to get the engine to start, and I often have to keep my foot into the accelerator a bit or it will stall. Once running, the engine seems to run fine. No error codes at this point.
So far I installed new plugs and a fuel filter with no change. I've tried a couple different PCM's, also with no change. Checked the cap and rotor - they looked good. I have spare parts, so I don't mind doing some parts-swapping diagnostics. TPS, Ignition Coil, and MAP are all easy enough to swap out, but I haven't yet.
I doubt it's the TFI or PIP, as my experience with those failing is that they are heat sensitive, and less likely to show evidence of failure when cold.
So far I installed new plugs and a fuel filter with no change. I've tried a couple different PCM's, also with no change. Checked the cap and rotor - they looked good. I have spare parts, so I don't mind doing some parts-swapping diagnostics. TPS, Ignition Coil, and MAP are all easy enough to swap out, but I haven't yet.
I doubt it's the TFI or PIP, as my experience with those failing is that they are heat sensitive, and less likely to show evidence of failure when cold.
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Fleet Mechanic
Joined: Nov 2011
Posts: 1,823
Likes: 43
From: New York
Haven't checked, but that's a good thing to check. You thinking fuel pump heading south? When I installed the new fuel filter a couple days ago I was surprised to find no pressure when I removed the line from the filter.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
If fuel psi is low, you could narrow it down to either a failing pump or leaking fuel injector.
I have encountered a similar problem with my '92. Luckily, fuel psi was fine, with key on, engine off. And it would hesitate during the hot weather, but only before starting the truck in the evening before work. 12 hours later in the morning, and it fired right up.
I swapped ICM, TFI, checked and swapped ECT and IAT sensors. I also pulled the SPOUT jumper, trying to isolate the problem.
So far my troubleshooting has me at fuel problem since I had dual tanks and neither had fresh fuel in nearly 9 months. Both tanks were completely full. I have been on vacation and haven't had time to drive it more. I was finally able to run the front tank down below a 1/4 tank and I'm just waiting to put fresh fuel in it.
I have encountered a similar problem with my '92. Luckily, fuel psi was fine, with key on, engine off. And it would hesitate during the hot weather, but only before starting the truck in the evening before work. 12 hours later in the morning, and it fired right up.
I swapped ICM, TFI, checked and swapped ECT and IAT sensors. I also pulled the SPOUT jumper, trying to isolate the problem.
So far my troubleshooting has me at fuel problem since I had dual tanks and neither had fresh fuel in nearly 9 months. Both tanks were completely full. I have been on vacation and haven't had time to drive it more. I was finally able to run the front tank down below a 1/4 tank and I'm just waiting to put fresh fuel in it.
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