EFIDynoTuning Forum

Engine will not start.

Previous owner claims after recent service he was driving and noticed the engine was overheating. Pulls over, coolant everywhere. Parks vehicle, comes back later and it will not start.

Removed and replaced all fuel.
Replaced fuel filter.
Good compression. Good fuel pressure.
Checked most COPS, all good.
IACV is open.
No damage to wiring or connectors found.
Verfied spark while cranking.
Bypassed fuel pump relay (always on)

Now here is the weird part. Pulled the starboard fuel rail, left injectors attached. (Unplugged COPS)

Turn key to on, then start. 5 pulses from the injectors, and fuel pressure drops from high 30's to mid 20's.

Injectors stop pulsing.

Let off start (key resets to run) and try to start again. No pulses. Try again, no pulses.

Turn key off and on, "start" again. 5 pulses then nothing. Reset to run, start, and nothing.

Engine does not fire at all, even with the 5 pulses.

Ohmed crank and cam sensors ~330ohms each. New sensor is 350ohms.

Inertia switch isnt tripped, not sure if that matters. Did not verify intertia switch continuity.

Lastly, tried to pull codes with Scan Gauge II, despite 'Service Engine Soon' light being on, no codes were present.

odd indeed

what caused it to puke coolant? if overheated due to fans not coming on i would suspect the ircm has failed.

5 pulses and nothing is very odd. If it were a theft fault it shouldnt even pulse. I dont think an rv would have pats though.

why is the pump wired to run non stop? pressure dropping is very troubling too.

sounds like your scan gauge isnt happy with that ecu. best bet is a cheap elm device and forscan to read codes.

what service did they have done?

The old man's daughter sold me the motorhome, the service was years ago, as was the overheating incident. He told her "engines blown"...

A crack head cousin and her friend lived in it for a year... then they stole it... then the daughter got it from Dad to fix up. They're cutting their losses. This is all of the info i have.

I bypassed the fuel pump bc its check valve has failed, and to make sure i had full pressure.

Fan is mechanical, not electric.

Try starting fluid in the throttle? If it fires on that it points to a fuel problem. 20 psi is too low As D said. You could have a weak pump and stuck injectors from sitting / gummed up.

might have jumped time, unplug the cam sensor and see if you get any kind of different response from the engine

doubtful that the injectors would be gummed since she pulses exactly 5 times every time

I've tried starting without the cam sensor, crank sensor, and MAP sensor. Engine response is the same.

What i cant understand, is after a start attempt, reset to run, and start again, i wait for fuel pressure to build back to 40psig, and no pulses.

I'm thinking the PCM has failed, or i'm wondering if there is something in its code where it will only command 5 injections if a condition isn't met. Might there be a transmission sensor that if malfunctioning, triggers a "no injection" response from the PCM?

Are there timing marks on the balancer and cam sprockets to verify valve timing? I googled and couldnt find an anwer.

cant start without crank sensor
there is no map sensor

yeah no pulses is odd indeed thats pretty baffling

nothing like that im aware of

no the transmission has no affect on the engine, even with the trans removed and mlps jumped itll startup and run perfect no problem

yes there is dimples on the sprockets. It takes about 64 revolutions to get them to line up though.

what is the ecu catch code ?

These are the digits on the PCM.
XC3F-CFD
MCM3

Now, in fairness, those codes are on the black box which houses the PCM. I have not removed the PCM to verify what codes it has on it.

Where is the MAF sensor located? On the port side of the engine, over the head, there is a smallish magnesium box with a 4? wire plug going to it, and a what appears to be a vacuum hose. I figured that was the MAP sensor.

have you tried squirting some gas or staring fluid in there and see if it fires up for a second?

yeah thats the catch code. Looks like that cal doesn't have pats so you shouldn't have a problem there.

maf should be in the inlet between the air filter and the throttle body.