Hi guys,

 

So today she finally died... went to go for a nice drive in the sun and it started but died after a couple of seconds, and then wont start. This is something that has been developing for a few months. occasionally not starting, then if I leave it for a couple of minutes it will start. The symptoms are that it will turn over but not fire. or fire first time and start, but then immediately die, by what seems like fuel starvation.

 

Also, I though I had worked out that if I hear the fuel pump prime it usually meant the car would start. this seemed consistent. If I didn't hear it prime then it wouldn't start, pointing to fuel problems.

 

This leads me to believe it could be the crank angle sensor, fuel pump or FP Control Module itself. I guess it could also be the ECU, although I am less likely to believe this would just start randomly playing up over a long course of 3 months without any other symptoms.

 

So my points to investigate would be first of all the connections and relays on the CAS, ECU, and Fuel Pump. if they seem fine I would then need to check voltages between cas > ecu > fuel pump. hopefully that will tell me whats what?

 

Anything I have missed?

a defective CAS can be diagnosed quite easily: start the car, do you see the tach moving while turning over, YES: CAS is ok, NO: CAS (may be) defective

 

if the CAS is ok, then it could be a defective PTU (Igntion Power transistor) or as you mention, the FPCU (fuel pump controller) has gone.

 

Try a good clean of the pins of the PTU first, sometimes it's just corrosion and a good clean with a dremel or sandpaper makes it work again

 

The FPCU can be (temporarily) bypassed to get the car going again (search on here or google)

 

The pump can only be heard priming after the engine has been off for at least a couple of hours.

It's rare for the pump itself to stop working completely all of a sudden...you should have had other signs before, like lack of power, very hard to start and other similar symptoms

Thanks Lymon, Really helpful!

I had an MX5 with a CAS problem.

Just like ur problem would start run & stop.

Erratic & frustrating even took it to an electrical car specialist.

AA thought it was the fuel relay too!

So I would say CAS

hmm yeah okay sounds similar! So is the tach meant to register something whilst cranking??... I thought that was only in the on position, not start.

Just tried it again after 3 hours... no fuel prime, but started and then stalled. This is a video of it subsequently cranking...

 

Make the vid public :yes:.

oops now published

is it worth trying to bypass the fuel ecu?

 

http://www.pexcom.com.au/z32cms/e107_plugins/content/content.php?content.369

 

if you want to try another one I have one you can have cheap as well...

 

I've also got a pump.

good plan.. will get some wire and give it a shot

Looks like CAS to me. Pretty sure my tach registers a few hundred rpm while cranking....and my car doesn't run very well at all at the minute. As said, you will only hear a fuel pump prime after it has been stationary for quite a while and the car decides that there will be no pressure in the rail. The CAS sends the 'engine cranking' signal to the FPCU and starts the fuel pump running constantly when the starter is turning.

Solved!... thanks to medallion man and lymon! :) FPCM at fault. Bypassed it and she primed straight away.

 

The hint for me was that it still wasn't priming today after sitting for two days! So that wouldn't be CAS, so got some wire and did a quick bypass and all good.

 

Med PM your way and some rep :)

Edited April 9, 201510 yr by wchestnutt

the question is... Can I get to work (50miles) running without a Fuel Pump ECU?... Apparently it will just idle a bit rich as it is runnign at the full 12v constantly. I am going to get one asap in the next few days anyway.

 

Any thoughts?...

I think mine was bypassed during a mapping run previously and has been running like that since.

bypassing the FPCU means the pump will always run at full blow/speed (and as a side effect the pump will be a little bit noisy)

It shouldn't have any effect on the fuel-pressure, unless your pressure regulator is shot.

 

for most aftermarket pumps it is recommend to bypass the FPCU, but a 20+ year old standard pump is not going to appreciate it suddenly has to work at 100% all the time and it'll wear out faster. (and a second hand FPCU is probably cheaper then a new pump)

My fuel pump ecu just had some dry joints that was causing similar issues. Easy to fix if it`s that.

hmm picked up another FP ecu and not fixed :( not sure why it worked when I first earthed the FPCM because it sure as hell wont work now. Fuel pump primed today but then died straight away again :s

 

Do the fuel pumps go on these cars? Cant find any info about it as a common thing. Is it worth jumping the fuel pump relay or is that what we are doing by bypassing the fuel pump ecu?

 

Maybe it is the CAS after all... I am going to get my mechanic to look at it I think :( Getting some serious zed withdrawal right now!!

AARGGG!!!

 

So i went to get my new fuel Pump ECU back and see if there were any burnt bits or dry solder. Thought would try once more to earth/bypass my old one...

 

first attempt nothing (I am not splicing into the cable as I don't trust myself to not cut straight through it).

second attempt - Bingo! Runs fine...

 

Unattached the earth and tried it again... Fine! And again, and again.

Tried the other fuel pump ecu I bought and again fine!...

 

Okay something is not right here. Just been for a drive around town for a bit of a blast and she is fine.

 

Also my driver side window is now working whereas it had stopped working for the last couple of months... must be coincidence right?

 

Really not sure what to make of this.. Could it really be just an intermittent CAS or something? and just by virtue of sitting there turning the key on and off a hundred times it ended up waking up?

 

Think I can safely rule out the Fuel Pump Control Module though.

 

Could this be the Fuel Pump Relay? Don't think it explains the fuel cut I experienced during driving a few times, but could explain the hard start. If anyone has one laying around I will buy :) none on the bay at the moment.

As said before I had a similar problem with an MX5!

AA man wiggled the fuel pump relay & it started!

Ran well for a few days then! Couldn't start the car!

Started next day like no problem!

Half way to 6 mile run it stopped & would not start! Left it there till I got back!

Four hours later it started!

Took it to car electric specialist, one week later after all tests!

Turned out to be the CAS!

Could be wrong though!

ahh okay mate that sounds promising then, extremely similar!! Thanks for the heads up. I will get my man to sort the other CAS :)