Warm Start Problem

So I have a warm start problem. It's 02 TD4, not had the carthat long. It starts fine when cold, starts with apush when warm (easily), when warm sometimes starts after cranking for about 20-30 secs but sometimes not. No smoke at any time.

Had a problem with the EML coming onwhich I think was low fuel pressure but cleared after running a couple oftanks with millers through.

Leak back test shows the injectors to be fine, removed & cleaned the sensor on the end of the fuel rail (low pressure sensor?), removed in tank pump (looks brand new) and can hear it run along with the underbonnet one when I turn the ignition on.

I read on a diesel engine forum that there's a solenoid somewhere near the fuel pump "that's held on by two torx screws and the seals can wear causing warm start problems". Anyone know what this is and where exactly can I find it?

Whatelse should I be checking?

Oh, when I did the leak back test I didn;t clamp the spill tube, i just put a cloth under the T connections. A lot of fuel came backup the spill tube. Is this normal? Not sure how fuel can return that way as I'm talking a steady stream of diesel comingback.

Fritz said:

I read on a diesel engine forum that there's a solenoid somewhere near the fuel pump "that's held on by two torx screws and the seals can wear causing warm start problems". Anyone know what this is and where exactly can I find it?

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Fuel pressure regulator on the rear of the HP pump (follow electrical connection) has a seal that can leak and allows fuel pressure to pass down the return line.

Faulty crank sensor, is a very common problem for your fault. Do a search on here and it will give you some idea about it. Easy to change and not to expensive

Thanks for the replies,I forgot to mention in my original post that before I ran the millers through it also seemed to take a long time to start from cold. Not ages but maybe 3-5 secs. Also, I removed & cleaned the connections on the fuel pressure sensor (at the end of the fuel rail), not the actual sensor so I guess that could still be suspect.

Anyway from your replies and other posts I've read I suspect the cam sensor, the crank sensor; the fuel pressure regulator: or the fuel rail sensor. Still along list!

a few more questions.

I assume the fuel pressure regulator can fail in two ways, either the O ring seal leaks (i.e. a fuel leak) in which case I should presumably be able to see some staining or the internals can fail resulting in too much fuel being sent back down the spill pipe. Chaser would this account for the fuel coming back up the spill pipe when I did the leak back test? Or is this normal to have fuel flow back the wrong way?

Also Booboodag if the crank sensor was faulty wouldn't I have the problem even when cold? Or lumpy or some sign during normal running. Would it just be a problem when the engine was warm? I did have a few incidents of the MIL light coming on when driving, at the time I cleared it by switching off/on and then it stopped happening after I ran millers through a couple of tanks. Could that have been an early sign of the crankshaft sensor failing?

I've read I can try removing the cam sensor and cool it down in a freezer to see if the engine then starts to see if that's at fault. Can I run the engine without the acoustic cover? Aany problems, other than it'll be noisier of course.

The prices I'm seeing are £ 75 each for the cam & crank sensor; £ 160 for a fuel pressure regulator; and £ 140 for a fuel pressure sensor although I understand there's a wiring re-work I should fit at the same time as well. This all adds up and if I can narrow the list down into order of likelyhood it might well end up saving me a packet.

Finally, is it worth seeing if there are any codes stored, a lot of posts seem to hint that they're not that helpful once you have them. But if they are whats the best way of going about this? My local main dealer wasn't really intrested when I spoke to them but quoted "about £ 100 + VAT" which seems unreasonable.

You only need the crank sensor for starting once running it takes no reading from it, so will run fine. Why it only affects warm starting is a something i don't think any one knows. But your problem is a classic sign of a crank sensor failing.
As for diagnostics most local independents will charge £30 to £40.
A problem with the fuel pressure sensor normally give poor performance when running

The fuel pressure reg seal would leak fuel internally down the return line.

When doing an injector leak test there is always some fuel that comes back up the spill return so it's normal to clamp it and therefore I can't say how much is acceptable. Excessive amounts could be coming back up from the fuel regulator.

The cam sensor is only used at start up. The crank sensor is in use at all times

thanks chaser, i just read my post and dont know why i said crank sensor and not cam sensor

Thanks for the updates,I decided to bite the bullet and had the local independant do a full diagnostic which came back with the fault "Fuel Rail Pressure Plausibility". Well I kind of new that already but it also gave a list of likely suspects one of which was injectors so they did a leak back test which then showed 3 leaky injectors despite my own efforts showing they were fine so I guess I managed to fluff it up somehow.

The attached sketch shows what the test kit looked like. Injector 1 had a little fuel showing up just at the bottom of the tube, maybe 2-3"; 2 was about half way up the tube; 3 went all the way to the little test tube thing at the top of the tube; and 4 had no fuel in the tube at all. So I guess I've at least got an injector problem.

Now the mechanic is saying that 1, 2, & 3 need replacing and if I'm doing 3 I might as well do all 4. I was frankly stunned when he told me how much he wanted to do the job.

My regular mechanic has quoted me £ 100 + parts

Anyway could you shed any light on the following?

Does injector 4 need to be replaced if it's fine at the moment?

Does injector 1 really need replacing?

If not any idea how much life injector 1 might have left?

Anyone know where I can pick up some good value injectors?

I'm thinking that when you did the leak test you didn't disconnect all injectors at once so the fuel from
the spill pipe was from the other injectors. :doh:


get a price from a diesel specialist to have all 4 refurbished.