R300 Won't Start/Run (under normal conditions)

[Andy Whittle]

Following a problem starting my car after the Poole Quay for my Car event a couple of weeks back I have been trying to find the cause of my problems.

 

Basically the engine was cranking fast but not starting. Eventually it started and idled without problems. I then pulled away only for the engine to die and again I had problems restarting but eventually it kicked into life. Since then I have not been able to start the car at all.

 

Car is an R300 (1.9 Scholar K-Series), with MBE ECU, Shurlock EP100 immobiliser (now removed), battery master switch, Brise starter motor, etc, etc

 

Fault finding carried out thus far:

Checked ECU fuse

Checked ECU plug is seated correctly, checked for damaged pins - none found

Checked fuel pump fuse

Checked fuel pump connector

Checked and by-passed the inertia cut-off switch

Checked/cleaned grey engine loom plug

Checked the battery master switch, seems to be OK

Checked battery is fully charged and holding charge (also tried using spare battery as booster)

Jump-started from another car (read in another thread)

Re-programmed immobiliser keys

Un-installed the immobiliser completely

Continuity checked from fuel pump socket to the grey engine loom plug

 

Other observations:

When the ignition is first switch on the fuel pump doesn't sound like it's priming

When I measure the voltage across the fuel pump connector and turn the ignition on the meter reads +12v and then falls to zero.

When cranking the engine the meter reads 12v at the fuel pump connector

The fuel pump runs if connected directly to the battery

The car will run with a direct connection to the fuel pump, it will also run if +12v is connected into the relevant side of the inertia cut-off switch

I've taken the cover of the MFRU and the relays seem to be operating correctly for starting.

 

I could power the fuel pump from a direct feed via a relay but this seems like a proper bodge job

 

What more can I try? Any pointers most appreciated…

 

Cheers - Andy

[rj]

Sounds like a dodgy relay in the mfru. Contacts do wear out. Not very often is it the coil, so it will move, but just not make contact.

[John Vine]

It certainly looks like a problem with the feed to the fuel pump.

I could power the fuel pump from a direct feed via a relay but this seems like a proper bodge job

But isn't that the same principle as the starter-relay mod? If RJ is correct (and I think he probably is), a bypass relay will be a whole lot cheaper than a new MFRU. Can you borrow a working MFRU from someone to help the diagnosis?

 

JV

[Andy Whittle]

Thanks RJ and John

 

After a lot of cutting and pulling I managed to get the MFRU apart. Loads of glue/sealant holding it together which makes me think it's been apart before .

 

Cleaned all the relay contacts and hey presto! I'm back in action

 

Interestingly enough the resistance across the fuel pump contacts wasn't very high before I cleaned them. It just shows that it doesn't take much to stop it working, especially when you take into account the length of cable and numerous connections the current has to flow through to get to the pump.

 

Now I have to put the car back together, but first I'll check and clean all the earthing points .

 

Cheers - Andy

[John Vine]

Well done, Andy.

 

JV