CIS - fuel delivery issue

Vincent 911 · 06:43 PM

I 'rebuilt' my 3.0L CIS this winter (964 cams, news head studs, valve job, SSI...). I started it two weeks ago and it ran for 20 mins (2000 rpm). It ran fine.
I shut it down and never started again: it is cold in MI and I am still working on the car. This week end I have changed a few parts up front: front shocks, front wheel bearings, brakes and turbo tie rods.

Here is my issue: this evening I turn the ignition key to check if the license plate lights are working (I don't cranked the engine) and hear loud whistling coming from the engine bay while the fuel pump was running. It seems the noise is coming from the injectors.
Actually I think the injectors are running because they is a little bit of fuel on the seals.
I checked my fuel distributor plate and it moves freely. It seems that the fuel delivery is wide opened. I may have fill the cylinders with fuel...

During the tie rod change I did removed the steel pan underneath the steering rack where is located my fuel pump. Could it be a return fuel hose bent?
Could it be a faulty fuel pressure regulator? Something wrong in the fuel distributor?
Why is it so sudden?

Thank you.

KFJ_SC · 01-30-2008, 08:00 PM

Vincent - the fuel pump *shouldn't* be running with just the ignition on - it works on a relay and should only come on when the starter is engaged or the engine is running. Is it possible you are hearing the CDI - this makes an audible whine in the engine bay. When you lift the air sensor plate, do you feel any resistance? If there's no resistance then the fuel pump isn't running. You could pull an injector and put it in a jar, turn the ignition on and see if there's fuel spraying. Unlikely, but possible some wiring got mixed up or the fuel pump relay is jumpered and the fuel pump is actually running.

psalt · 01-31-2008, 03:13 AM

There is a safety switch on the fuel distributor (air flow sensor contact) to prevent the fuel pump from running when the engine is stopped. It could be unplugged or not making contact.

Vincent 911 · 01-31-2008, 04:32 AM

KFJ_SC, I am 100% sure it is not the CD. I have already heard the CD box and it is much quieter than the noise I heard yesterday evening.
Concenring the relay here is what I can say:
- without the fuel pump relay the pump does not work with ignition ON
- with the fuel pump relay connected the pump works with ignition ON
Could it be a bad relay?

psalt, it sounds you may be right. I will check this switch connection tonight.

Thank you.

KFJ_SC · 01-31-2008, 05:18 AM

Sure sounds like the relay is stuck in an on position. Swap it with another to test.

CliffBrown · 01-31-2008, 04:52 PM

Vincent

Injectors will definitely whistle when fuel is flowing through them.

It's entirely possible that's what is happened. Fuel is not supposed to flow through the injectors with just the ignition key in the on position but these are old cars and some of the relays and electrical connections to prevent this are not always doing their job.

I see two problems, 1) fuel pump running, 2) injectors flowing fuel without motor running (air sensor plate raised).

I see a lot of SC with a fuel pump running with the key in the on position but the injectors should not flow fuel (whistle) unless the air sensor plate is lifted or the motor is started.

Your air sensor plate might be hung-up or the fuel distributor plunger might be stuck open. The plunger can get stuck with a motor that hasn't been operated frequently.

Vincent 911 · 04:42 AM

Quote:

Originally Posted by CliffBrown

Vincent

Injectors will definitely whistle when fuel is flowing through them.

It's entirely possible that's what is happened. Fuel is not supposed to flow through the injectors with just the ignition key in the on position but these are old cars and some of the relays and electrical connections to prevent this are not always doing their job.

I see two problems, 1) fuel pump running, 2) injectors flowing fuel without motor running (air sensor plate raised).

I see a lot of SC with a fuel pump running with the key in the on position but the injectors should not flow fuel (whistle) unless the air sensor plate is lifted or the motor is started.

Your air sensor plate might be hung-up or the fuel distributor plunger might be stuck open. The plunger can get stuck with a motor that hasn't been operated frequently.

Thank you Cliff.

1- Yesterday I swapped the fuel relay with an other one. And it works: the fuel pump is not running anymore with ignition ON. By chance I have an other SC in the garage

2- Concerning the plunger stuck that might be true. The car has not ran frequently during 5 years... That does not prevent the car to start good... What can be the issue with a stuck plunger?
How can I let the plunger free? If I drive the car like that could the plunger get free?

Thank you.

Vincent

CliffBrown · 02-01-2008, 09:11 AM

Driving the car should help and hopefully the plunger will start to operate properly once the old fuel is flushed from the fuel distributor.

Be careful not to get raw fuel into the cylinders when the motor is not running, it's very easy to cause damage when you try to the start a motor with a hydraulic lock.

Vincent 911 · 02-01-2008, 09:42 AM

Quote:

Originally Posted by CliffBrown

Driving the car should help and hopefully the plunger will start to operate properly once the old fuel is flushed from the fuel distributor.

Be careful not to get raw fuel into the cylinders when the motor is not running, it's very easy to cause damage when you try to the start a motor with a hydraulic lock.

Cliff, I turn the engine by hand yesterday evening. It was OK. I will let it "dry' at least the weekend.

Thank you,

Vincent