Sorry about the length of the post just thought it would give the best overall view of the problem.

Just purchased lovely red 1997 4.6 HSE approximately 400 km away from home base here in Australia.

Checked oil level before leaving its previous owner, was on full mark.
200 km of cautious driving on moderately busy roads then stopped for the night.
After half an hour checked oil it was still just on the full mark.
Left early next morning very little traffic and after warming it up drove with a little bit more sprit.

Basically 100 km on I had to slow to a crawl for road works.
OIL LIGHT CAME ON. I was able to pull over safely in maybe 300 metres and switched off.
Bonnet up left it for 15 minutes then dipped the oil.
OVERFULL by about 10 mm still oil coloured not milky. Water level in the expansion tank was a little over its cold pointer.
Must be petrol in oil, thus diluting it, so pump could not maintain pressure at low revs.

Started motor, oil light on and clattering noise in top of motor.
Possibly valve / tappet area so very quickly shut motor down.
Seven hours later a tilt tray arrived from the breakdown assist organization I belong to.

I thought I had purchased a very well maintained two owner car. It looks good, but not serviced very regularly.

Put engine flush in oil. Drained it … bottom of bowl covered in balls of sludge.

New 20w 60 oil. Regular day time temps mid 30° c, 280,000 km on motor. My other P38 runs well on it.
300 ml Lifter/Tappet Fix & 300 ml MoS2 moly.di oil additive.
New filter.

Air temp sensor sprayed with MAF cleaner. New air cleaner element. Date on old one 2013.

MAF sensor and inside of its housing was black … took a lot of cleaner to get clean.

New fuel filter. You wouldn’t believe the muck that flushed back out of it.

New PCV valve … old one seized in housing took some getting out. 2 New associated hoses.

Sprayed contact cleaner on all the plug/sockets I could find in engine bay.

Fitted 2 new exhaust oxygen sensors.

Used Nanocom Evolution to reset Adaptive Values.

Started motor, on idle the top end noise not as bad. After 30 minutes on idle much quieter. Switched off.

In the morning put 200 ml oil in to bring up to full. Started it up, top end noise disappeared after a minute. Let it idle up to 68° c . Checked for fault codes. The only one that has ever showed up was
0183 ….. “Fuel temp sensor a circuit high input”. And it had now disappeared.

Took it for a drive, keeping revs down, 10 km all looking & sounding good.
Turned round, then 5 km short of home engine running rough. Only way to get home was to travel slowly & blip throttle. Possibly to use up excess petrol?? Slow speed into driveway oil light came on. In to garage motor off.

Checked oil level 15 minutes later, YES it was 5 mm over full !!
Next morning still over full but started easy. NO oil light on, idles well @ 650 rpm, warmed up to 70°c, can be reved to 2000 rpm all smooth & sounding good.

Injectors putting too much petrol into motor when driven ??

New Battery fully charged.

Any ideas where this 70 + year old should look for a solution.

Andrew
Bank 1
Pre cat O2 sensor (V) 0.02 to 2.7
Fuel trim long term % 0
Fuel trim short term % 1.25 to 5.0

Bank 2
Pre cat O2 sensor (V) 2.3 to 2.6
Fuel trim long term % 0
Fuel trim short term % - 1.25 to 2.5

Adaptive FMFR gm/s 0
Fuel Temp (C) - 255.00 ??
Fuel Level 1.46
O2 configuration 11
Pre Cat O2 Sensor Heater 1.13

Current throttle pos (V) 0.58
Stored throttle pos (V) 0.58
Adaptive air flow (kg/h) 0
Current air flow (kg/h) 21.59
Intake air temp (C) 15
Air flow sensor (V) 1.42

Secondry air status (on/of 4
Curr.run line position 31
Long term adaptive idle 43
Short term adaptive idle 43
Idle speed reference (rpm) 633
Idle air control valve (%) 74
Coolant temperature (C) 68
Battery (V) 16.00 HIGH ??

Last thing first, it's a well known bug with the Nanocom that it often reports the battery voltage at 16V when it isn't, so that can be ignored.

Pre-cat sensors should flip flop between 0V and 5V, 0V showing rich, 5V showing lean, so they are both suggesting a rich mixture.

Fuel temperature of -255 suggests the sensor is open circuit. To check if it is a sensor or wiring problem, with a 1kOhm resistor in place of the sensor, you should see a temperature of around 40 degrees C being reported. The fault code appears when the fuel temperature and the coolant temperature are so far apart that one or other is obviously incorrect. However, the main function of the sensor is to richen the mixture on a hot start to compensate for the fuel vaporising in the rail and shouldn't have any affect if it thinks the fuel is really cold.

However, one thing you haven't checked and could well point towards the cause of the problem, is the fuel pressure. There is a Schrader valve on the RH side of the fuel rail (above cylinders 4 and 6) so you can check it there, it should be 34-37 psi (use a tyre pressure gauge if you have nothing else, just make sure you blow the fuel out of it before checking your tyre pressures). The GEMS has a fuel pressure regulator on the rear of the fuel rail (hiding under the throttle linkage) with a reference pipe to the intake manifold. Two possibilities come to mind, one is that the fuel return pipe is blocked so excess fuel can't be returned to the fuel tank which would show up as high fuel pressure. The other is that the diaphragm in the pressure regulator is split so fuel in being injected into the intake manifold. In that case the pressure will be correct but the engine will be running rich, particularly at idle. Disconnect the pipe that goes from the pressure regulator to the intake and start the engine. If fuel comes out of the pipe, then that is your problem.

Bloody hell I only went to get a morning cup of tea and there's a reply already.
Thank you
I will definitely look into those areas after breakfast.

Andrew

When you are I. topping up and ii. measuring are you definitely doing so under identical conditions? I suppose temp will have a big impacr, and whether or not the engine is running or the oil is all sat in the sump... I wonder if it's worth doing a second oil change, if it had loads of sludge

hi Andrew, welcome to the pub, being an Aussie like me you would be accustom to a night at the pub. when you try all the things Richard has mentioned your next thing would be a compression test, its not uncommon for v8s to carry a dead piston,eg cracked, top come off etc. to get that much fuel in a short time would indicate a big issue. take the oil filler cap off and see how much blow by is coming out of the tappet cover, if its bad then the compression test will show the dodgy piston. it should have a vacuum on the filler cap.

RedP38 wrote:

I only went to get a morning cup of tea and there's a reply already.

If Gilbert/Richard isn't doing something unimportant like going to France or getting married, (or something important like fixing others P38s) he monitors both sides pretty well to answer questions (and delete spam).

th.

Thanks to all for ideas.
Rather slow to get important things done like working on P38, as other things keep happening in general life that need fixing.

Re fuel temp sensor I will get a 1kOhm resistor on Friday when I go to town.

Local hardware shop had a pencil type tyre pressure gauge so have used it.
Ignition switch in pos 2 seems to only work the pump for a short time, take a couple a readings and virtually nothing. My 1998 one is the same, anyway......

Pos 2 in the region of 8/10 psi (other car 7 or so psi) Engine on idle 28 psi (other car only has 17 psi and it runs very well).

So 28 psi is down from the stated 34 to 37 psi. Might make an attempt to get it checked by a local mechanic but won't be able to fit that in until next week ... the busy life of pensioner!!!!

Tried the pipe off the pressure regulator no petrol came out while the engine on idle.
I put a piece of clear hose on it in a loop and went for a drive it did not show any sign of having had petrol in it.
The original hose was very old a crack was starting in it .... so I will replaced it.

The car always starts the moment the key is turned to the start position cold or hot.
Another 20 km trip yesterday (Wednesday) afternoon, revs kept to below 2000 rpm running well stopped twice idle was good.
Just before home increased speed to 100km /h and roughness came in requiring blipping of the throttle to induce kick down then run okay. But now into 50 km zone short way into driveway back to a perfect idle.

My very smart other half came over to state " well the exhaust doesn't stink of petrol today".
I checked the oil and it is just a as yesterday slightly over full so no change there.

For any important checking of the oil level I have vehicles on the known level concrete.

Off to start another busy day
Andrew

RedP38 wrote:

the busy life of pensioner!!!!

Tell me about it. I've been retired almost 5 years now and wonder how I ever got time to go to work. A pair of P38's and a 4.3 litre V6 boat to look after, daughter's car, son-in-law's car, wife's car and now step daughter has just bought a little Toyota Aygo that needs a few jobs doing on it. When I'm not installing air conditioning heat pump systems that I started doing after retiring.

My very smart other half came over to state " well the exhaust doesn't stink of petrol today".

That's a good sign. Whatever the problem was, you seem to have fixed it. Which is always a worry as you don't know what you did to fix it and still won't know what it was you did that fixed it.

Yes, the fuel pump runs for a couple of seconds when the ignition is first turned on to put some pressure into the fuel rail and then runs during cranking and once the engine starts.

MAF sensor not only deals with fuelling but also has control over gearchanges and kickdown. So that is another thing that might be suspect even though the reported airflow at 21.59 is about right at idle. It should be 20 +-3 rising to 60 +-3 at 2,500 rpm. If it is reading wrong at higher revs, that will cause gearchanges to not happen when they should.

Once again I apologize for the long post it is an attempt to give a full picture of my problems.
If the moderator sees it as space wasting I will understand his use of the delete button.

Before the holiday break I used a pencil type tyre gauge to test fuel rail pressure and got 28 psi at idle
After the break a chap came round with his EFI test gauge and got the same 28 psi, with 36 psi on blipping the throttle.

I ordered a test gauge for myself, but when it arrived they had sent the large Schrader connector, I am still waiting for the correct fitting to arrive.

Last weekend I finally got time to install a new pump unit that I had bought in Dec 2023 to fit in another P38, and that didn’t happen. It came from Paddock UK was supposed to be OEM but the packaging was Britpart Made in China, at the time I paid AU$196.

Engine on idle, using the tyre pressure gauge at the rail valve the new pump delivered guess what 28 psi !!!
When the EFI connector arrives it will probably confirm that 28 psi to be correct.

Yesterday I tested the voltage at the pump connector several times turning ignition switch to position 2.
Result was 12.6 volts from a battery voltage of 12.9 volts, so that’s ok. Although the voltage would be slightly more with the motor / alternator running.

So that I could have the motor running and test some pressure I went on to cobble fittings and EFI hose and gauge together, but could only use them to replace the fuel filter.

• Engine on idle only recorded constant 32 psi and blipping the throttle 38/40 psi. Still not the 34 to 37 psi expected on idle, and that is at the tank !! On switching off it held 28 psi for some time.

I can’t see that a brand new Mahle fuel filter, when in place, would drop that 32 psi to 28 psi at the rail valve.

• Why would the old pump and the new pump only record 28 psi at the fuel rail ??

• So are the pumps not able to deliver 34 to 37 psi at idle due to their brand and country of origin ??
The old pump was supposed to have been replaced some time ago by previous owner, he’s not sure when.

• Or is there a faulty component or restriction that is not allowing the pump to develop its full pressure ??

• Can a faulty FPRegulator restrict the pump developing its pressure ??

New vacuum hose on the plenum to the fuel pressure regulator. While doing that I temporary “T” jointed a vacuum gauge into the line it was recording steady 14 in/hg.

No fuel comes out of the disconnected vacuum hose from FPR when engine is on idle.

I have replaced the flexible EFI hoses on the two metal pipes coming up to the bulkhead. (for safety)
When the return hose was off I could easily blow down it so no obstruction there.

I have replaced the faulty Fuel Temp Sensor.

On the one test across the pins of the Coolant Temp Sensor when the Nanocom was registering 86° c it was
250 ohms, 50 below the manuals 300 ohms so I have a new one on order.

Today, Tuesday, I took the car out and did 100km mostly at 90/100 kph. With very little hard acceleration.
Towards the end of the run, going up fairly steep hill, it briefly ran roughly, I planted the right foot and it kicked down and took off, I then eased off to resume normal running.

As I slowed to turn off the highway the oil light started flickering and at slow revs came on steady. Soon home and switched off.

• An hour later checked the oil dip stick and the level was 10 mm too high. When I left it was a couple of mm under full. So when it goes on a longer run and gets really hot there must be surplus petrol and it goes in the sump.

Water level in the hot expansion tank is as you would expect just over the full arrow mark. No engine over heating.

Cold or hot the engine starts straight away.

• What is the German made canister between fuel hose and screwed onto the fuel rail? ?
Can’t find it in works manual or parts manual.

There was a slurry/dirty petrol mix that I got out of the fuel filter. I have never seen a fuel filter in such a state. So is it possible that some of the mix could have been forced through the filter and be in that canister causing a restriction ??

I was going to put a couple of photos of the canister and slurry in this, but have no idea how it can be done.

My wife has named the car “ The Bimbo” looks good visually but lacking on the more important mechanicals.

Thank you
Andrew

Sorry if I missed any points.

The fuel pressure regulator doesn't leak any fuel through the vacuum connection when you simply disconnect the pipe but maybe it leaks some fuel when engine vacuum is sucking on it?

With what you've said about petrol getting in oil, got to wonder if an injector is sticking open and putting in too much fuel which sees fuel get past piston rings and into oil. A bad enough fuel leak could maybe also explain the low fuel pressure reading. But if an injector put that much fuel into a cylinder we might expect that cylinder to misfire.

Simon beat me to it. The fact that you've got an intermittent rough running and fuel in the oil, it might be that you have a fuel injector sometimes sticking open. That will bucket fuel into one cylinder so it runs ridiculously rich, lambda sensor will detect that and lean off the mixture. So you will have 1 cylinder on one bank still running rich while the other 3 will be running lean. Pull the spark plugs and look for one that is black to see if you can identify which one it might be.

The cylinder thing where the fuel pipe joins the fuel rail, is there to smooth out the fuel flow rather than have it arriving in pulses.