We haven't seen or worked on this machine for a few years, but the customer called the other day, no starting. One of my techs went out, I don't remember the code, but it could be the cam or crank sensor and he replaced both. He mentioned the cam sensor plug was cracked up on the outside. After this, he finally got it started and found he had a bad miss on one cylinder he thought. I ran him a compressor pressure tester to site, and checked again and found #3 and 4 cylinders not firing. We checked compression. Had well over 210 each, checked for an intake leak. All seemed fine. We installed new spark plugs in 3 and 4 ( yes- the special ones) and no help. We then swapped 3/4 coils with 1/2 coils and now 3/4 will run the engine, but 1/2 are no longer contributing. So.... We ordered two new coils and I went myself this morning to install. I tried to start the machine when I arrived, but it would crank and die. Installed the two coil packs, same result. I checked the 5 amp fuse at the injector and found that it was fine, but I would get a blinking voltage there, then when it started, the blinking would stop and the engine would die. I pulled the busted up plug loose from the cam sensor and I then get no "blinks" at the fuse, so this seems to indicate the problem?? Any ideas out there?
Nissan MCUL02A33LV
SN 9Q0119
Showing items 31 - 45 of 46 results.
This may sound crazy but I've had this type of issue with Toyotas. The ignition timing gets severely retarded while cranking. Try checking the timing while cranking vs running to see if there's a difference.
If there is then what I did to confirm voltage drop as it's cause was to jump the starter with another battery altogether (jumper battery for starter totally it's own circuit-not connected to forklift at all) & then check timing while cranking- in my case the timing didn't change in this scenario. Not sure it's applicable but I thought I'd share
Those are some good points BB. It seems that once the engine reaches operating temp it starts right up. To get it started when cold, I can shoot throttle body cleaner into the air cleaner on the OHG post or pull the air cleaner elbow and pour in a cap full of gas. Once it starts it runs great. Climbs ramps, idles great, etc. The low pressure vapor line seems to be fine. Earlier in we had ordered a new Nikki regulator, my tech had determined that that pressure was a little high- we ended up pulling it back off when it didn't help (and have since put it back on). When the old regulator was back on, I tapped into it and showed the pressure was slightly high (with a simple dial gauge) but stayed steady enough during the attempted crank cycle, so it seems the lock off is doing ok. I still may bypass it to eliminate the possibility of it being a problem that you had. Thanks for the suggestions!
You say it starts & cuts out when cold- how long does it have to run for this symptom to go away? How do you keep it running to get past this start/stop issue?
A few things to ponder- how's the fuel line from the regulator to the fuel injector assy? Any chance of a slight rub through, tar build up, etc?
Secondly-How's the fuel shut off solenoid? On occasion I've had them open enough to give initial pressure to the fuel system to start but not enough to allow the engine to run. Once the tar softens the symptom goes away- doesn't happen often but once in a while.....
BBF, here's the update. Customer went to use it today for the first time. Starts and dies.... Same as before. Apparently the machine got hot enough before to continue starting. We will carry on again tomorrow.
Sure doesn't take much on these newer trucks to have a fuel problem since they run so lean. I feel your pain having to call the dealer- but sometimes you gotta do what you gotta do.
Here is the update for anyone interested. I bit the bullet and had a tech from the Nissan dealer come out with a laptop. It turned out that our fuel pressure from the regulator was 28 kPa (about 4 psi) measured with the fuel pressure sensor, he tapped out the dirty LP fuel filter just prior to the regulator, and got us up to 33 kPa which let it start and run great. 35 kPa is spec (just over 5 psi) which a new filter I have ordered should get us too. Now- it sure doesn't seem to make sense, especially since it ran great if you got it started, but that was the cure. I'm glad to have it running!!
one question, is this a gasoline or LPG truck? If LPG,it sounds to me like a possible tar build up issue in the air mixer/injector. Remove the inlet line from the converter to the mixer and see if there is tar/debris built up on the "last chance" screen it will be under the LP inlet nipple,can remove the two small bolts that secure it to the mixer to take it off,just watch for the small clip that holds the screen in place.
Check your lp injector, the assistant injector is used for cold start enrichment, possibly giving enough fuel to start, but the main injector may not be supplying enough fuel to keep the engine running. Also check your lp pressure at converter should be between 4.5 and 5 psi. You need to determine if the condition is due to too much or not enough fuel, the fact that it runs good warm makes me lean towards the converter.
A little more info. After starting with a small cap of gasoline AND letting the machine warm up, it continued to start great. Even after sitting for several minutes. So it appears that when cold, it's gonna continue to start and die/ start and die. Has anyone seen this before?
This girl runs too smooth for that. Once I got it started, and it warmed up, it started right up every time. I'm going back in the AM and see what it does cold.
I just had one of those K25's that cracked the intake manifold causing starting, skipping, and idling problems. That round shaped runner heading to # 3 and #4 cylinders.
Ok, I'm back to customers. There is no code on the dash, my tech came by- pulled air cleaner cover from "carb", poured a cap full of gasoline inside , put cover back on along with bolts and snugged. The engine started and ran on all four cylinders (I had installed the two coil packs). So it appears that my problem goes away after starting. Any thoughts??
Thanks for the reply. Sorry, can't access with PC, but will be back there in about 1.5 hours and will recheck for dash codes.
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