The V8 Owners Forum -

Hi all as per the title if the injectors was worn blocked or just dribbling fuel when they shouldn't be firing into the cylinder. I'm getting a loss off power when hot. Parts replaced have been the pressure regulator found it was jammed closed. Fuel pump as a precaution fuel filter was changed also as I had no idea when it was last changed. It has had some fuel treatments run thourgh the tank. Is it possible that with the damaged pressure regulator that it could have caused too much pressure in the fuel system causing the injectors to leak fuel past there seats these haven't been removed or tested. But now I'm getting good performance bottom to mid range top range off the revs it isn't giving as much performance and also it seems to be starting to pop thourgh the gear changes when I boot it. A new set off spark plugs is being fitted tonight see I that help clears the problem. Thanks micheal

Any one at all. I have droped a bottle off injector cleaner in the tank and run it for 50 miles with the injector treatment in the tank ontop off the fuel treatment and there was a big improvement in the power off the engine I am just wondering if there is a answer as to why this is.

Hi
to me it sounds like you have an air leak, this being masked by the odd dribbly injector and acceleration enrichment when accelerating through the revs then showing itself again when you lift off the throttle.
Have you checked for split pipes fron the AFM to the plenum and generally around the inlet manifold? WD40/brake cleaner will show it up for you.
Best regards
Mike

Big woof wrote: I'm getting a loss off power when hot.

It would be a mixture problem, most likely. But too weak or too rich?

Go for a run until you experience the problem and shortly thereafter check the plug condition, one from each bank!

Black/wet = too rich. White = too lean.

Now we have some clues to work with.

I think you will find it will be too lean - just a hunch?

Filter was changed also as I had no idea when it was last changed..

At least you'll know it's OK, but hopefully the fuel tank and the pump are not affected by Crud in the tank, causing a restriction on how much fuel can be supplied at full throttle.

It has had some fuel treatments run thourgh the tank. .

Those treatments can also encourage the crud in the tank to become detatched from the inside walls and block the system - If so clean out the tank and any pre filter inside and the pump and the fuel lines.

Is it possible that with the damaged pressure regulator that it could have caused too much pressure in the fuel system causing the injectors to leak fuel past there seats these haven't been removed or tested.

The maximum pressure the pump can deliver is about 50 - 55 psi, well within the capacity of the fuel lines and the injectors so they should not leak.

You can test for leaking injectors quite easily.

Fuel Pressure Checking
• SAFETY WARNING: Under operating conditions the fuel injection system is pressurised by a high pressure pump operating at 26 to 36 psi. When the engine is stationary this pressure is maintained within the system.
• To prevent pressurised fuel escaping and to avoid personal injury it is necessary to depressurise the fuel injection system before connection of a test gauge or any servicing is carried out.
Depressurising the Fuel System
• Remove the fuel pump relay located behind the passenger glove box to immobilise the fuel pump.
• Start and run the engine to use up the fuel in the fuel rail, the line pressure will drop and the engine will stall.
• Switch the ignition off and disconnect the battery.
• Fuel at low pressure will remain in the system which can be released by removing the cold start injector from the plenum chamber and placing it in a suitable container.
• Release the hose clip and carefully remove the hose from the injector to discharge the remaining fuel into the container.
Pressure gauge
• Connect a suitable pressure gauge to the injector hose.
• Refit the cold start injector to the plenum chamber, refit the fuel pump relay and re-connect the battery.
Testing the Fuel Pressure Regulator
• Remove the air filter from the airflow meter, switch on the ignition and operate the flap in the air flow meter by hand to energise the fuel pump.
o The fuel pressure should be 35 - 37 psi.
• Switch off the ignition.
o The fuel pressure should remain at 35 - 37 psi
• The fuel pressure may fall very slowly due to inconsequential weeping in either the fuel pressure regulator valve, the fuel pump non-return valve or any of the injectors.
o A slow steady fall is acceptable but a rapid fall must be investigated
• If the pressure test is unsatisfactory the most likely cause of the problem is the fuel pressure regulator.
o Replace the fuel pressure regulator with a new or known good substitute unit
• If after fitting a known good regulator and re-testing the system, the pressure continues to fall rapidly check the following until the cause is found.
o The fuel injectors
o The fuel pump non-return valve
o The fuel system pipe-work
• Depressurise the fuel system again before removing the test gauge.
• After final reconnection of the pipes check for fuel leaks at all the joints both before and after the fuel injection system is re-pressurised.
Conclusions
• So many problems can be attributed to the Rover Efi fuel system due to fuel flow and fuel pressure issues and because of the age of these cars the primary cause is liable to be fuel contamination due to a broken tank filter allowing crud into the fuel pump and beyond.

I'm getting good performance bottom to mid range. Top range of the revs it isn't giving as much performance.

This may be another sign of restricted fuel supply.

seems to be starting to pop thourgh the gear changes when I boot it.

Sounds like the transmission kick down function is working OK, so the engine is beginning to deliver more torque and the transmission is responding correctly.

Sounds to me like fuel starvation if it's only happening at high revs/load - I assume you don't thrash the engine when cold.

I'd first check the actual fuel pressure - regardless of what parts you've replaced. You should see at least 36 psi if you run the pump with the engine stopped. If it's low, do check you are getting the full battery volts both in and out of the pump relay, with the pump running. And about 9 volts at the pump - again with it running, assuming it has the normal resistor in line.

A trick we used to do on the old Mercedes Bosch systems to test for leaking injector seals was to drip a little oil around the bottom of the injector and if the seal is shot, the oil will pull into the gap and that will allow the engine to idle smoothly because there is suddenly no air leak.