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hello all,
it takes 3 or 4 runs of the starter motor to get it to fire. sometimes it throws random codes then. If I clear the codes after starting no more codes appear.
Glow plugs appear to be working.
I think I read somewhere that the MAF sensor could affect starting, is this correct?
Any other clues
Thanks Peter

An update
I cant find any fuel leaks , no air in the system after 10 hours of sitting.
I have ordered new fuel filters just to be sure.
Ditto new MAP sensor on the way.
Haven't looked at the electrical side of things, leaving that till last, don't enjoy playing with things I cant see .

phum wrote:

You can "See" the grounds, at least check them to rule them out...

That's the correct part number. Many are running the GM MAP sensor including myself and not getting any codes due to it.
Could a new one be bad, it is always possible.
You stated you had a lot of corrosion under the battery, did you check those ground wires?

I cant find any fuel leaks , no air in the system after 10 hours of sitting.
I have ordered new fuel filters just to be sure.

While reading the following, keep in mind that I'm not a fan of throwing parts at a problem. With that said, here's my 2¢ regarding air in the fuel:
This is a problem that can be difficult to convince people they're experiencing - at least, it certainly was in my case, and I know that I wasn't the first to be stubborn about it. Last Friday, I finally installed an in-tank fuel pump and (even with other issues going on), there was a noticeable improvement in starting, idle, and responsiveness. There are other things that need to be addressed that I'm getting ready to go outside and tackle, but until I could feel the difference between not having an in-tank pump and having one, the reasons for installing one were largely academic. Sure, I knew it would be an improvement over stock, but because the KJ was basically working I largely considered the upgrade to fall into the category of, 'it'd be nice to have one day'. I'm now of the opinion that it should be one of the first upgrades done on these vehicles.
I'm mentioning this because you're in a similar boat to me (multiple issues at once), and are going down some of the same troubleshooting paths. I didn't have fuel leaks either (air-in-fuel is typically caused by suction of air into the lines, not leaking of fuel, so you may not see fuel leaks), and two filter changes didn't make any difference, even with the revised fuel filter head in place.
I'm not saying you have to install the in-tank pump right away by any means, but it does sound like air in fuel is an issue for you. I don't doubt that there are other things also going on, but you may want to give this upgrade more consideration than you might have been.
Out of curiosity, you say that there's no air in the fuel. How did you test for that?

Author:	phum [ Fri Sep 06, 2019 8:51 pm ]
Post subject:	hard to start
hello all, it takes 3 or 4 runs of the starter motor to get it to fire. sometimes it throws random codes then. If I clear the codes after starting no more codes appear. Glow plugs appear to be working. I think I read somewhere that the MAF sensor could affect starting, is this correct? Any other clues Thanks Peter

Author:	flash7210 [ Fri Sep 06, 2019 9:28 pm ]
Post subject:	Re: hard to start
1. It’s not the MAF sensor 2. Maybe the codes are not random. They might actually help diagnose the problem. 3. Is the engine getting fuel? Is there air in the fuel? When was the last time you changed the fuel filter?

Author:	phum [ Fri Sep 06, 2019 9:56 pm ]
Post subject:	Re: hard to start
Is the engine getting fuel? Is there air in the fuel? When was the last time you changed the fuel filter Yes, no air, starts the same if it sits for 10 seconds or 10 hours. The only code that seems relevant is map sensor which I have cleaned but to be sure I have a new one coming.

Author:	WWDiesel [ Fri Sep 06, 2019 10:51 pm ]
Post subject:	Re: hard to start
phum wrote: hello all, it takes 3 or 4 runs of the starter motor to get it to fire. sometimes it throws random codes then. If I clear the codes after starting no more codes appear. Glow plugs appear to be working. I think I read somewhere that the MAF sensor could affect starting, is this correct? Any other clues Thanks Peter The MAF sensor will not affect or prevent the engine from starting, it is only used for EGR operation. You have some other problem. Air in fuel causes lots of issues on these vehicles. That is why many install a in-tank lift pump to eliminate all air in fuel problems. What were the codes? Knowing them may allow some on this forum to offer help and suggestions.

Author:	TKB4 [ Fri Sep 06, 2019 11:16 pm ]
Post subject:	Re: hard to start
It would be best to record the codes and share them with us even if they seem random. The behavior sounds like restricted fuel flow or air in fuel as Flash alluded to. You might want to make 100% sure that the lift pump is actually functioning and fuel head line fittings are tight. I suppose it could be early crankshaft sensor or cam sensor failure failure even if no codes at all. You might also want to check the air filter. I assume you have the newer generation fuel head. Need theses things to ignite: Fuel from injectors in adequate amounts and pressure (ECM must be satisfied to signal injectors) Air in correct Ratio Compression of adequate degree at correct timing with valves etc I seriously doubt compression is a problem or timing valves etc since the engine does start but that leaves the other two as the most likely possibilities Good luck in deciphering the cause.

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Author:	phum [ Sat Sep 07, 2019 2:58 am ]
Post subject:	Re: hard to start
codes that I have seen are P0146 U0002 P08C1 P20C1 P0108 P2001 P0234 P2004 Plus a few others that only relate to gas engines. These codes only occur when trying to start, when motor is running no codes. I have a completely custom fuel filter system and an inline pump with no evidence of leaks fuel out or air in. Air filter I haven't looked at but its not old, will try without it.. It runs perfectly once started that why I am inclined to think its electronic but where to start

Author:	Jay ne Ohio [ Sat Sep 07, 2019 5:04 am ]
Post subject:	Re: hard to start
I agree with the others. Sounds like air in the fuel. I just fixed one of mine. It had started leaking fuel back by the rear axle due to a pin hole in the steel line but would start and run fine. I cut out a section of line and replaced it. That stopped the leak, but then I started getting air in the filter. When I repaired the steel line, I had to rotate the plastic line at one of the press on connections. It would let air in but did not leak a drop. It took a lot of cranking to get it to start, but it would start. I dropped the fuel tank, removed the plastic line, installed a rubber line directly onto the fuel tank, secured with a stainless worm clamp, then coupled the rubber hose onto the steel line with a stainless worm clamp. Primed the filter and it starts instantly now.

Author:	flash7210 [ Sat Sep 07, 2019 6:46 am ]
Post subject:	Re: hard to start
Yes, your MAP sensor appears to have a problem P0108-MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT HIGH. P0234-BOOST PRESSURE SENSOR NEGATIVE DEVIATION. Its either a bad sensor or a problem with the wiring to the sensor. I know on my engine it wont run with the MAP sensor unplugged.

Author:	TKB4 [ Sat Sep 07, 2019 9:16 am ]
Post subject:	Re: hard to start
or it could always be another electrical problem like a bad ground, but favor the Map or its wiring also. What makes me think it could be ground is the numerous seemingly unrelated codes. BTW the other codes you said only apply to gassers may also apply to the CRD just maybe not point to same etiology. Good luck with the new MAP sensor I believe this will solve your issue.

Author:	WWDiesel [ Sat Sep 07, 2019 2:31 pm ]
Post subject:	Re: hard to start
I would still check those grounds to rule them out. No cost and does not take much time. Especially the one on top of the finder behind the left headlamp, several have had issues with it. grounds:

Author:	GordnadoCRD [ Sat Sep 07, 2019 3:11 pm ]
Post subject:	Re: hard to start
Have your battery load-tested. Check and clean every connection between it and the starter. Some earlier OEM starters draw a higher amp load than newer ones.

Author:	phum [ Sun Sep 08, 2019 6:18 pm ]
Post subject:	Re: hard to start
An update I cant find any fuel leaks , no air in the system after 10 hours of sitting. I have ordered new fuel filters just to be sure. Ditto new MAP sensor on the way. Haven't looked at the electrical side of things, leaving that till last, don't enjoy playing with things I cant see .

Author:	WWDiesel [ Sun Sep 08, 2019 9:51 pm ]
Post subject:	Re: hard to start
phum wrote: An update I cant find any fuel leaks , no air in the system after 10 hours of sitting. I have ordered new fuel filters just to be sure. Ditto new MAP sensor on the way. Haven't looked at the electrical side of things, leaving that till last, don't enjoy playing with things I cant see . You can "See" the grounds, at least check them to rule them out...

Author:	GordnadoCRD [ Sun Sep 08, 2019 10:02 pm ]
Post subject:	Re: hard to start
WWDiesel wrote: phum wrote: An update I cant find any fuel leaks , no air in the system after 10 hours of sitting. I have ordered new fuel filters just to be sure. Ditto new MAP sensor on the way. Haven't looked at the electrical side of things, leaving that till last, don't enjoy playing with things I cant see . You can "See" the grounds, at least check them to rule them out... A battery load test is also a "quick-n-easy" any auto parts store (NAPA, Auto Zone, etc) can do for you. Make sure they understand you want the BATTERY load tested, not the alternator. Clean and tighten terminal connectors is another common problem source that takes minutes to check and service.

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Author:	phum [ Sat Sep 14, 2019 1:35 am ]
Post subject:	Re: hard to start
Another update. All electrical checked, cleaned and functioning. glad I did because I removed the battery tray and there was a lot of corrosion underneath. Replaced MAP sensor with GM bit 55206797 ( couldn't get genuine here) Starting better but now getting MAP code instantly. Have I got the wrong sensor or is it possible to get a new one that's bad? Thanks all

Author:	WWDiesel [ Sat Sep 14, 2019 1:53 am ]
Post subject:	Re: hard to start
That's the correct part number. Many are running the GM MAP sensor including myself and not getting any codes due to it. Could a new one be bad, it is always possible. You stated you had a lot of corrosion under the battery, did you check those ground wires?

Author:	phum [ Sat Sep 14, 2019 2:14 am ]
Post subject:	Re: hard to start
WWDiesel wrote: That's the correct part number. Many are running the GM MAP sensor including myself and not getting any codes due to it. Could a new one be bad, it is always possible. You stated you had a lot of corrosion under the battery, did you check those ground wires? Yes, no corrosion there but body was well insulated with paint, suppose it earthed through the thread. paint is gone good contact now between lug and body plus bolt, same for the other earth mentioned earlier

Author:	TKB4 [ Sat Sep 14, 2019 9:44 am ]
Post subject:	Re: hard to start
It appears at least the ECM (computer) still thinks there is something wrong with the MAP system. I know you said the electrical checks out but if you haven't already removed the connector of the harness to the ECM you might do so even if nothing appears wrong just removal and replacement may improve the connection as well as maybe remove and replace the MAP sensor plug a time or two. Yes the new MAP sensor could be bad but I have not heard of a new one that was bad as I have heard of other new sensors being bad.

Author:	casm [ Sat Sep 14, 2019 10:17 am ]
Post subject:	Re: hard to start
phum wrote: I cant find any fuel leaks , no air in the system after 10 hours of sitting. I have ordered new fuel filters just to be sure. While reading the following, keep in mind that I'm not a fan of throwing parts at a problem. With that said, here's my 2¢ regarding air in the fuel: This is a problem that can be difficult to convince people they're experiencing - at least, it certainly was in my case, and I know that I wasn't the first to be stubborn about it. Last Friday, I finally installed an in-tank fuel pump and (even with other issues going on), there was a noticeable improvement in starting, idle, and responsiveness. There are other things that need to be addressed that I'm getting ready to go outside and tackle, but until I could feel the difference between not having an in-tank pump and having one, the reasons for installing one were largely academic. Sure, I knew it would be an improvement over stock, but because the KJ was basically working I largely considered the upgrade to fall into the category of, 'it'd be nice to have one day'. I'm now of the opinion that it should be one of the first upgrades done on these vehicles. I'm mentioning this because you're in a similar boat to me (multiple issues at once), and are going down some of the same troubleshooting paths. I didn't have fuel leaks either (air-in-fuel is typically caused by suction of air into the lines, not leaking of fuel, so you may not see fuel leaks), and two filter changes didn't make any difference, even with the revised fuel filter head in place. I'm not saying you have to install the in-tank pump right away by any means, but it does sound like air in fuel is an issue for you. I don't doubt that there are other things also going on, but you may want to give this upgrade more consideration than you might have been. Out of curiosity, you say that there's no air in the fuel. How did you test for that?

Author:	WWDiesel [ Sat Sep 14, 2019 1:48 pm ]
Post subject:	Re: hard to start
casm wrote: While reading the following, keep in mind that I'm not a fan of throwing parts at a problem. With that said, here's my 2¢ regarding air in the fuel: This is a problem that can be difficult to convince people they're experiencing - at least, it certainly was in my case, and I know that I wasn't the first to be stubborn about it. Last Friday, I finally installed an in-tank fuel pump and (even with other issues going on), there was a noticeable improvement in starting, idle, and responsiveness. There are other things that need to be addressed that I'm getting ready to go outside and tackle, but until I could feel the difference between not having an in-tank pump and having one, the reasons for installing one were largely academic. Sure, I knew it would be an improvement over stock, but because the KJ was basically working I largely considered the upgrade to fall into the category of, 'it'd be nice to have one day'. I'm now of the opinion that it should be one of the first upgrades done on these vehicles. I'm mentioning this because you're in a similar boat to me (multiple issues at once), and are going down some of the same troubleshooting paths. I didn't have fuel leaks either (air-in-fuel is typically caused by suction of air into the lines, not leaking of fuel, so you may not see fuel leaks), and two filter changes didn't make any difference, even with the revised fuel filter head in place. I'm not saying you have to install the in-tank pump right away by any means, but it does sound like air in fuel is an issue for you. I don't doubt that there are other things also going on, but you may want to give this upgrade more consideration than you might have been. Out of curiosity, you say that there's no air in the fuel. How did you test for that? Very true! To build on what Casm stated. Air in fuel can be a very difficult thing to determine for sure. Short of installing some clear tubing to watch for air bubbles, infused or emulsified air in fuel can very difficult to spot or prove. Top mods that should be done to these vehicles's engine ASAP if you have one. 1. Total removal of the EGR system (top priority) 2. Install of an in-tank fuel pump 3. Replace MAP sensor 4. Replace Crankshaft Position sensor The list goes on and on, but the above have proved to be some of the most troublesome causing items.