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Car won't start

Greenie - 22/6/22 at 07:32 PM

Hi all looking for help.

I own a SSC Stylus which runs a C20XE built by SBD Motorsport. It's running throttle bodies and MBE 956.

On Saturday I went out for a nice little run out, and it ran great. Parked upon return and left for a few hours before starting it and reversing it into the garage. Started no problem at all.

On Sunday I went to get it out and it wouldn't start, turned over but no fire. I have tested the spark at each lead and all seems good, it's getting plenty fuel, checked all connections etc. Changed the cool pack with a spare which came with the car.

It just ain't having it totally stumped.

How can it be great one day and not the next.

Really would appreciate any help and advice.

Oddified - 22/6/22 at 08:29 PM

If you haven't already, get easimap on a pc connected to the ecu, check everything is showing sensible readings/values such as air/coolant temperatures, and throttle position (closed/idle should be site 0.0). When cranking, rpm would normally be around 150 - 200 rpm.

The 956 is a fairly simple ecu, not many inputs/outputs so there's not much to go wrong.

Mr Whippy - 22/6/22 at 11:08 PM

Well if you've checked and there is a strong spark at the plugs and not even one cylinder is firing, then it must be the fuel.

What happens if you squirt some petrol into the throttle bodies...does it try to fire?

Greenie - 23/6/22 at 06:33 AM

Thanks for the prompt reply.

Not easy to download the version of easimap4, need a prehistoric laptop which will take pre windows 2000.

There is loads of fuel getting in, but maybe edging towards contaminated fuel, banged a couple of gallon in on the day before it stopped working.?

nick205 - 23/6/22 at 09:21 AM

quote:
Originally posted by Mr Whippy
Well if you've checked and there is a strong spark at the plugs and not even one cylinder is firing, then it must be the fuel.

What happens if you squirt some petrol into the throttle bodies...does it try to fire?

That'd be my first line of attack - if you have a can of "Easy Start" a spray of that in the intake when cranking normally gets it going (if only briefly). That would help identify if it's a fuel issue.

adithorp - 23/6/22 at 10:30 AM

When you say "loads of fuel" do you mean at the fuel rail or are the plugs wet? If the plugs are dry then check the injectors aren't firing.

Mr Whippy - 23/6/22 at 11:56 AM

quote:
Originally posted by adithorp
When you say "loads of fuel" do you mean at the fuel rail or are the plugs wet? If the plugs are dry then check the injectors aren't firing.

ditto it's something very straightforward

BenB - 23/6/22 at 12:22 PM

quote:
Originally posted by nick205

quote:
Originally posted by Mr Whippy
Well if you've checked and there is a strong spark at the plugs and not even one cylinder is firing, then it must be the fuel.

What happens if you squirt some petrol into the throttle bodies...does it try to fire?

That'd be my first line of attack - if you have a can of "Easy Start" a spray of that in the intake when cranking normally gets it going (if only briefly). That would help identify if it's a fuel issue.

That was my thinking. Blowtorch the plugs if they look flooded to dry them out and then crank it and ASAP squirt some of that stuff in. That should get it to make some noise before the plugs flood!!!
Another thing would be to use an inline ignition tester to check that the plugs are truly sparking when under compression. It's unlikely all the plugs would stop sparking but a poor spark from the driver/coil could result in a situation in which the plugs will spark when out of the cylinder but fail to spark when under compression.

Greenie - 23/6/22 at 05:46 PM

It's getting plenty of fuel into the cylinders.

Really beleive it's bad fuel.... going drain it off at the weekend.

I will keep you all updated.

I am in a fortunate position that I work in the parts industry. Do parts are on sale or return.

Mr Whippy - 23/6/22 at 09:21 PM

quote:
Originally posted by Greenie
It's getting plenty of fuel into the cylinders.

Really beleive it's bad fuel.... going drain it off at the weekend.

I will keep you all updated.

I am in a fortunate position that I work in the parts industry. Do parts are on sale or return.

Diesel

Greenie - 25/6/22 at 02:23 PM

Quick update

He car has a low pressure fuel pump from the tank to a swirl pot then a high pressure to the fuel rail, so I thought I would use the low pressure pump as a method of taking the fuel from the tank, took the feed off at the swirl pot and it just trickles then gives up, but the pump is still ticking as normal.... low pressure facet pump goosed???

adithorp - 25/6/22 at 02:28 PM

Or filter/pipe/intake blocked. Facets usually don't tick when they've failed.

Confused how it had "loads of fuel" if this is the case.

Greenie - 25/6/22 at 02:35 PM

Exactly ..... this has got me stumped .

Mr Whippy - 25/6/22 at 03:36 PM

probably just full of crap, time to strip it down but at least you've found the fault.

rusty nuts - 25/6/22 at 08:21 PM

Screw in filter blocked, had the same problem with my facet

pigeondave - 26/6/22 at 08:57 AM

Sounds like a quick blast with an air line back up the pipe.

No airline? Use an electric tyre inflator with the lilo attachment. Fuel will go everywhere a d you will melt the tarmac.

Could it be that the fuel tank. Is rotting from the inside?

SJ - 30/6/22 at 08:56 AM

Mine did something similar and it was gummed up fuel in the fuel filter after the tank. New filter and it was sorted.

Greenie - 30/6/22 at 06:09 PM

Working my way through the fuel system, which as you can imagine ain't a pleasurable job, but as I do I now find that the high pressure fuel pump and filter are cable tied together under the inner wing to a broken clamp.... need to dig deeper is to see what other outrageous issues I find.

pigeondave - 1/7/22 at 12:26 PM

Just get it working first, the suspense is killing me.

You can tuck all the wires back up and go for a drive

Greenie - 2/7/22 at 03:31 PM

Here we go with today's efforts..... Changed the fuel, tested the compressions and all great, retested the spark all good... disabled the fuel pumps and squirted raw fuel into the throttle bodies whilst cranking and she fired up, completed the exercise time and time again and exact same result, ran until fuel was burnt off. So now I am looking at fuel pressure issues.

What's your thoughts?

adithorp - 2/7/22 at 06:11 PM

quote:
Originally posted by Greenie
...So now I am looking at fuel pressure issues.

What's your thoughts?

I thought that was what was concluded after your low pressure pump couldn't empty the tank?

Manually fill the swirl tank and then see if the high pressure pump will run it.

pigeondave - 3/7/22 at 03:39 PM

Similar to what Adi said, but take the pipe off and see if the low pressure fills the swirl. I put the hose into an empty petrol can so any crap got pushed into the can.

Then if that's all good on to the high pressure pump, if that's good. High pressure regulator, assuming you got a return line to the swirl pot?

adithorp - 3/7/22 at 04:39 PM

quote:
Originally posted by Greenie
Quick update

....so I thought I would use the low pressure pump as a method of taking the fuel from the tank, took the feed off at the swirl pot and it just trickles then gives up, but the pump is still ticking as normal.... low pressure facet pump goosed???

That would seem to indicate we already know it's the LP pump or supply to/from it. So checking the HP as I suggest would confirm that if it then runs. Then check feed pipes and LP filter (my personal no one suspect).

Greenie - 11/7/22 at 06:17 PM

Still at it....

Fuel tank,fuel pumps/lines, fuel pressure all fine.

Crank sensor, temp sensor and throttle sensor all ok.

Great spark.

Disabled the pumps and sprayed Easy Start into the throttle bodies and it started and ran in a fashion until I stopped spraying. Tried this with the pumps enabled and it flooded as such.

I am of the understanding that the injectors batch fire at a pulse rate, so made a home made Noid light using a low watage 194 bulb, tested each injector lead under cranking and was expecting to see the bulb pulse, no such luck the bulb stayed on and did not pulse, this was the same result on each injector, now this is telling me that the injectors are all been held open allowing far to much fuel into the engine simultaneously.

Further investigations are being made....

obfripper - 12/7/22 at 12:22 PM

I had similar problems when i first built my megasquirt, the fet driver chip failed, which then left the injectors permanently open with ignition on. The fet driver was a known issue at the time, and had been respecced for a more esd tolerant and pin compatible part.

I doubt there is a schematic for the mbe ecu, but you could trace back on the pcb to find which mosfet(s) and driver chip are used, if it's surface mount components you'll need to find someone who specialises in electronic repair to replace the affected components.

It may be possible for this to be caused by a short in the loom, if you disconnect the ecu connector and check resistance to earth on the -ve trigger pin of an injector, a short in the loom would remain with the ecu unplugged, an ecu fault would only occur when connected.

Dave

obfripper - 12/7/22 at 05:17 PM

It also may be worth messaging Ian Oddie on here, he repairs the older mbe ecus and may know exactly what's up from your symptoms.

https://www.locostbuilders.co.uk/members/Oddified/

Dave

Greenie - 22/7/22 at 06:41 PM

Finally got to the route of the problem, it's all comes down to a fault in a RACE TCS kit which had been fit by a previous owner, it had interfered with the injectors by sending a signal to keep them open, by passed the unit and it fired up. Hence the RACE TCS system is to be removed, i was never going yo use it, no need for it.

Just sits on 3000 revs, but a least it's running.

Thanks a million to you all for the help and advise..👍👍👍👍