Hyster H70FT:
No spark #1 and #4 cylinder

No 1 and 4 cylinder not firing ( no spark) swapped coils still no good. No codes showing up just not seeing any broken wires any were. Any one have a idea on what to check.
  • Posted 1 Jun 2016 03:58
  • Discussion started by Frindtracing
  • Pennsylvania, United States
Showing items 1 - 2 of 2 results.
@ frindtracing "I fixed it!" and, I took pictures.

Seems there is a pigtail from the main harness (starter side) that originates right under the piping into the injection manifold, then continues twisting first on one side and then through a lifting mount, under the O2 and thermal water sensor then terminates at the dreaded coil.

So, inside this pigtail is a heatshrink, thick rubber thingy. *NOITCE* there are 5 wires generated from the starter side yet only 4 that terminate into the coil pack. This is because a 5V wire actually terminates via 2 seperate 'resistors' into each white wire that terminates into the coil pack. This means one red 5v wire feed the coil and the other feeds each side of the coil. In my case because of the fact that the 02 and water were on top of the coil wires, and, the way they were wound, threaded, through the lifting bracket one of the legs of the resistors broke.

There fore this lift truck had intermittent seizures of only one side of the coil pack operating and this just happened to be on the 1/4 side. If it can happen to the 1/4 side it can happen to the 2/3 side of the coil as the 5th wire, which is red, terminates under the thick rubber heat shrink thingy but it actually has those afore mentioned resistors that it feeds into those white wires.

K, what I did as piks will show is, is that I tined each side if the broken leg of the resistor then stuck them together, vinal/black taped the white wires with the red and resistors and taped the plastic wire shroud back on AND instead of going through the lifting bracket I went over the top of the of the engine right into the coil pack. I then zip tied the 02, water sensor, and the ciol wires to the motor lifting brackets. And, the 70 is now running great and better than before because the intermittent coil firing has been fixed to a solid factory connection.

I ordered the pigtail and will replace my temporary fix and keep the temporary for a spare as there are two more 70's to fix plus a 90 and a 100 that are currently dead in the water or doing the '6th sense'....you know...the I see dead people thing? Well I see dead forklifts cuz they are actually there...

This site will not let me post piks and my morning time is getting short so I will give you all the pigtail harness #.

GFI
A7-274 REV C

SCT
A7274 REV C
  • Posted 10 Sep 2021 21:17
  • Reply by michael59
  • Oregon, United States
Old post but relevant subject, relevant because this is exactly what I am going through. Want to hear the tail of tears and woe? Thought so: So the 70 was running smoothly and then it would load up, load up as in full throttle and a snail could get along faster. Turn it off and let set and varoom off she would go; this tells me it is electric.

So then it starts with the popping and cutting out but every time the driver brought it to me it was running smoothly....till it din't. At that time I pulled singular wires off of the coil pack and they all had big spark but the engine still was running ruff which told me fuel. And, then the insanity started.

I have three 70's that do not run so I have available parts to swap out, the third 70 is the one I am talking about. So, I took a coil off of one of them and it made no difference. Took a coil off a second one and no difference, so I switched that thingy that is under the air box, you know the sealed electric apparatus with the three cam over connections. And, it ran better but ran like a tortoise and real ruff. I figured it might be the transmission filter so it got changed out Wednesday morning because it was heavy and only a cup of transmission fluid came out of it. The traveling was faster but it was still running ruff.

So between two forklifts I swapped parts, (this is where the insanity started,) and I found that the 1/4 side of the coil was not active. I could only swap between two lifts, (swap electrical parts,) because the apparatus on the third lift had different numbers than the other two.

Now here is what I do not understand: How can only one side of a coil pack fire and only fire on all three coil packs? Remember: The original parts were firing both sides of the coil but now there is only spark on the 2/3 side of the coil. The only firing one one side tells me that the problem is in the electrical thingy that attaches under the air filter/box. But how can two of them be bad? So the problem is located elsewhere, but where?

Today I am going to swap out, (or at least take a look at,) the electrical plug in box that hangs on the inside firewall to the right of the drivers knee, but I do not think it will change anything because I do not think that the pick up spark travels to the console before it travels back to the coil. BUT, I could be wrong because the lil led screen does have the words "cranking" and that shows that something travels to the console.

So there ya have it, the reason this old post is still relevant.
  • Posted 9 Sep 2021 19:21
  • Reply by michael59
  • Oregon, United States

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