01 Won’t start without priming
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Trailering
Joined: Jul 2024
Posts: 18
Likes: 1
01 Won’t start without priming
Hey guys. Had a quick question with my 01 with 250k. I’ve put 100k on it without a single hiccup but the other day after driving for 20 min and stopping at the post office I went out to fire it back up and she just cranked with no fire. Then I turned the key over to the on position for a couple seconds like I was needing the glow plugs and it started just like normal. I had to do that the rest of the day. When I got home I changed out the fuel filter (which had less than 1k miles on it) with a new one (oem) thinking maybe a fuel issue? That solved the problem for one day and now it’s back to needing to be turned on for a couple seconds first or it will just sit there and crank, no start. It’s not a big inconvenience but I imagine it’s a sign of something wearing out and needing replaced? Also it’s summer here in Oregon so I’m pretty sure it isn’t a fuel temp/glow plug issue. Any ideas would be much appreciated. Thanks
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
I'd start with checking the fuel pressure. It could be the pump getting weak or you've sprung a suction side leak that's causing the pump to struggle. There's a simple pressure test method in the tech section that should get you started.
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Trailering
Joined: Jul 2024
Posts: 18
Likes: 1
Thank you
Ok I got a test kit and hooked it up to the fuel bowl. I honestly couldn’t get it to read anything on the gauge but went ahead and swapped out the spring in the pressure regulator since it was easy to get to and a friend recommended it. After doing that I cycled the key back on and it shot to 80 psi and appears to not be having the problem anymore. Is that too much pressure? It was the blue spring that supposedly is an upgrade. Also, the psi slowly dropped as it sat there. Is that normal? I appreciate the help guys. Glad I got a tester.
Thread Starter
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Trailering
Joined: Jul 2024
Posts: 18
Likes: 1
I drove it around yesterday and sure enough, it wouldn’t start without priming again. Got home and hooked up the pressure test kit and it’s holding steady at over 80 psi while running. Now I know that’s too high so I figured I’d just replace the blue spring with an oem one but if the psi is so high why won’t the thing start without priming? Obviously the psi will naturally drop when you shut it off but is it supposed to drop to a smaller pressure then hold that to enable fuel to get to the injectors quickly when starting? And for some reason my system is dropping to zero psi so it will just crank unless turned on for a couple seconds first? I’m kind of at a loss here. Maybe the screens on the fuel pump need cleaned out? I’ve had fuel with sediment in it clog up tractor filters before so maybe the same thing happened here? But wouldn’t that keep it from reaching such high psi at the fuel bowl? It’s got my mind running in circles over here haha. I definitely appreciate the help guys.
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Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
Check the stand pipe in the fuel bowl just for giggles. It's the black tube in the center that you slide the filter on. It has a little valve assembly in the bottom that prevents fuel from getting to the rails if the filter isn't in place and fully seated. Many many people have been bit by that guy. A lot of people just gut the tube to prevent it but your call.
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Lead Driver
Joined: Jul 2017
Posts: 6,861
Likes: 2,335
From: WV
Mine will drop to zero with key off. That’s normal.
I usually pause for a second after key on to let the system prime before cranking. Of course when the engine is cold I’ll let the glow plugs do their thing before cranking, but that’s a different scenario.
You might consider driving it around with the gauge where you can see it for a while. That way you can check fuel pressure while it’s acting up. This is why many of us will recommend a dedicated fuel pressure gauge which normally very boring but extremely helpful in cases like this.
For the FPR I normally recommend getting the full rebuild kit instead of just the spring. The plunger and seal can wear and is part of that kit.
My guess is dirty in tank filters, suction side leak, or the broken pickup like oldmechanic mentioned.
I usually pause for a second after key on to let the system prime before cranking. Of course when the engine is cold I’ll let the glow plugs do their thing before cranking, but that’s a different scenario.
You might consider driving it around with the gauge where you can see it for a while. That way you can check fuel pressure while it’s acting up. This is why many of us will recommend a dedicated fuel pressure gauge which normally very boring but extremely helpful in cases like this.
For the FPR I normally recommend getting the full rebuild kit instead of just the spring. The plunger and seal can wear and is part of that kit.
My guess is dirty in tank filters, suction side leak, or the broken pickup like oldmechanic mentioned.
Thread Starter
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Trailering
Joined: Jul 2024
Posts: 18
Likes: 1
I pulled the fuel filter off and the stand pipe seemed fine. I pulled it out and removed the check valve assembly just to be safe and reinstalled. Nothing changed. Still will just crank if not primed. I think it’s time to drop the tank and clean those screens. Does that seem like the logical next step? But first I have to ask, what’s a side suction leak? It sure seems like I’m losing pressure somewhere I’m not supposed to be as soon as I turn off the engine and that’s what’s making me need to reprime every time. Obviously pulling the fuel pump and cleaning the screens would be a good thing to do regardless, but I don’t get how I could have such high fuel pressure at idle, have it running perfectly, then as soon as I shut it off it loses prime and that would be a dirty screen problem. Think I’m on the right track but dropping the tank next? Thanks again guys.
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
A suction side leak is a fuel system leak between the intake (suction) of the fuel pump and the fuel pick up inside the tank. They allow the pump to draw air into the system which diesel engines don't like plus the pump has to work harder to maintain pressure and overcome the loss of efficiency.
If you've still got the factory in tank mixing chamber/filter screen BS then yes this is as good a time as any to address the problem area. I'd read up on the Hutch and Harpoon mods in the tech section and Google and consider just deleting that whole mess.
If you've still got the factory in tank mixing chamber/filter screen BS then yes this is as good a time as any to address the problem area. I'd read up on the Hutch and Harpoon mods in the tech section and Google and consider just deleting that whole mess.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Yeah, broken record here. But this, in my opinion completely eliminates any need for priming the fuel system. Forever. Doesn't matter what conditions, engine temperature, or anything else I can think of. Engine starts right up without any delay or need to wait for the fuel system to pressurize. Fuel pump is submerged 100% of the time unless it gets run out of fuel so it never loses prime. Yes, it's a project to get it done. Yes, you have to drop the tank if you have to service it. But I did this modification probably 15 years ago now and I haven't had to drop the tank since then for any reason.
On the other hand, have you checked your HPOP function? Engine oil thins out when it's hotter and if there's an issue with that system it will show up more so when the engine is still hot and the oil isn't all thick like when it's cold in the morning. It will take some extra starter time, or in your case some priming to get the engine running and operating at a higher RPM than when cranking and that may be what is required to get enough HPOP oil volume going enough to drive the injectors.
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
Because so many guys are obsessed with throwing stupid amounts of money away on crap for no better reason than it says AirDog on it. Plus they read where someone they've never met put one on his truck they've never seen and it was awesome. The problem is "Awesome " subjective, your awesome and my awesome are likely very different. Without quantifiable data it's all just smoke.
