Hyster S50FT:
Engine locks up From LPGas When Cold & Cranking

So heres a good one. I have a 2006 with a Mazda 2.2 with a Asian fuel system on it. Truck has 3400 hours on it. We own it. I am an Independent lift truck company owner.
So I find when cranking engine its getting to much fuel through the injector nozzle & it locks up the motor while cranking so bad that the starter nose is ready to break off. It will start but every 4-5th crank rotation it locks up. Its done this since I bought it 4 years ago. If its 65 degrees or cooler it will do this. It will start normal once the machine is run for 3- 5 minutes. It just needs to produce a little engine heat & then it will start normally.
It is for sure getting a 6-8 PSI burst of intermittent pressure from the regulator because I checked inline fuel PSI.
So I replaced the $600 regulator & it still acts the same. Now what?
Unplugged the MAP,still does it,checked the POT. Its good. Verified there is no fuel leaking past the fuel injector nozzle while cranking engine over with injector electrically unplugged. Also no fuel is going through the power valve hose to the carb while cranking. I can make the problem go away by squeezing the injector fuel line & restricting the amount of fuel.
I spoke with 4 Hyster techs yesterday to find out they haven t run across this issue. I know all 4 guys,2 are road techs that have been their for 30 years & are sharp. The one tech said that Hyster engineers said that having a 6-8 # spike is normal when first starting unit. I disagree,I think I have another bad regulator. The strange thing is once you run the engine for 3-5 minutes the problem is gone. Fuel pressure won t spike anymore after its run just a little while.
There is a temp switch sensor mounted to the lp regulator. This is new with the new reg.. Could this be the culprit,Or the injector ?
Truck operates normal during warm up period. No codes. Oh & it has the correct injector nozzle per service gram.. Engine temp sensor is connected.
What do you guys think????
  • Posted 6 Nov 2015 01:42
  • Discussion started by Horse
  • Wisconsin, United States
Jeff Bykowski
Showing items 1 - 7 of 7 results.
Turned out to be old software from 2005 on a 2006 unit. Updated software & problem is gone.
Thanx for your replies.
  • Posted 17 Dec 2015 04:19
  • Reply by Horse
  • Wisconsin, United States
Jeff Bykowski
if the ground lead is failing, the electrics will find a path to ground, sometimes through the diff and frame trunion. have you tried just adding a regular jumper cable between the bell housing and battery neg while it is struggling to pull the engine over?
  • Posted 16 Dec 2015 10:51
  • Reply by edward_t
  • South Carolina, United States
"it's not rocket surgery"
Verified ignition timing & timing belt. Not sure if I mentioned this but I R/R fuel trim valve & the lean code is also gone now. Adjusted the accelerator cable to throttle pot ratio. Pot wasn t activating until 45 %. Truck isn t as doggy. Its making better power.
Still locks up. Had to take it to a Yale Dealer yesterday. I think its a software up date issue. Tech said it had the original software 5.1???
  • Posted 16 Dec 2015 01:25
  • Reply by Horse
  • Wisconsin, United States
Jeff Bykowski
make sure the ground connection between the frame and block is good and not corroded where it meets the frame and the block.
  • Posted 13 Nov 2015 06:25
  • Reply by edward_t
  • South Carolina, United States
"it's not rocket surgery"
It very well may be. We just verified timing with a light & it was advanced about 4-5 degrees. We set it where its suppose to be & the engine is a Dog. I suspect the belt/cam is off a cog. We will see?
  • Posted 13 Nov 2015 05:54
  • Reply by Horse
  • Wisconsin, United States
Jeff Bykowski
Propane will not lockup an engine. If the mixture is too rich it simply dumps the excess fuel out the exhaust. It sounds like a timing issue.
  • Posted 13 Nov 2015 00:32
  • Reply by BREWSKI
  • Nebraska, United States
confirm timing belt is dead on.
  • Posted 6 Nov 2015 23:29
  • Reply by edward_t
  • South Carolina, United States
"it's not rocket surgery"

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