988f series 2 no / hard start...

[rmllarue91]

Hey hef heres my latest project. 2zr??? Hrs 37000 It will usually start if plugged in. Almost no chance if not. It will run on starting fluid fine but doesn't help it start. I got a couple screen shots from et to upload I'm leaning towards injectors. It cranks about 230 rpms with booster. If I boost heui pressure on et it will start. But just cranking it will hold 1000 psi it will demand like 3100 and most pump will put out is 2800. I didn't pull covers yet and look for leaks they want to use tomorrow. But the pressure is higher with warmer oil in my head that doesn't seem like a high pressure leak. But I know there's lots of info out there on these so I figured I'd ask people familiar with it. Thanks

 

[rmllarue91]

 

[rmllarue91]

 

[rmllarue91]

 

[rmllarue91]

 

[Nige]

Diagnosing injectors can be kinda fun. Can you get hold of an electric porta-power pump..?
If so, pull all the valve covers and hook the pump up and pressurize the HEUI system for that head to about 2500-3000psi. Look for oil spewing out of the port in the bottom of each injector (the green passage above where the arrow "Adapter" is pointing). That signifies internal wear and means the injector is toast.



Also check what Part Number of injector you have installed and what Part # of software is in the ECM. Everything ought to be sorted by now but there is an outside possibility that the installed software and injectors may be a less than perfect match.

A good test of HEUI system performance is to get the Desired IAP and Actual Injection Pressure up on the ET screen and watch how fast the Actual IAP rises up to the Desired IAP while you're cranking the starter. The electronics will not come out to play until the Actual IAP is higher than the Desired IAP.

HEUI engines like a high cranking speed. I would reckon 150 RPM as a minimum. Might be worth checking.

 

[rmllarue91]

Hey nige I do have a single acting port a power is there a procedure or can u explain where to feed there's fittings in the center of heads where pressure censor for heui pressure is that a option. It's number 3 oring boss. Another thing I noticed is if I demand pump to raise pressure for it to start if I drop it back to 1000 psi before it's warm it will stall.

 

[rmllarue91]

It cranks with booster about 230 rpms
It will don't build as much pressure as demands by 300 psi

 

[Nige]

On one head you'll find the HEUI pressure sensor, on the other head it's generally a blanking plug in the same location. You can go in there.
What you'll have to do is blank the lines back to the HEUI at #10 & #15 on the illustration below otherwise if you fail to build pressure you won't be able to tell if it's going back through the HEUI pump or leaking from somewhere within the heads. At one time we had a kit of blank plugs for this job, I'm sure it went in the scrap bin 10 years ago.

 

[komatsukid]

Dead head the pump. What happens?