No start

[porschedavid]

1989 PORSCHE 944 2.7
Turns over but wont start no fuel getting to plugs
Replaced fuel regulator,fuel pump.Checked injectors wires with noid lights all ok.
bypassed dme relay.
Still no fuel getting to plugs.

[944 Ecology]

Remove fuel rail, place injectors in soda bottles, remove ignition coil wire to distributor cap, crank engine. If no fuel in bottles, check for fuel pressure at end of rail, or clogged injectors.

[porschedavid]

I pulled off the fuel rail and put cups under them and turned engine over ,but no fuel in cups.also fuel pressure is ok

[944 Ecology]

Sounds like bad injectors. Have them cleaned and tested at Witch Hunter in Washington State.

[Jfrahm]

Had the car sat for a long time? If so then yes the injectors are likely plugged up. You can clean and backflush them at home but a pro job is better. At home you can rattle the injector with a 9v battery and blow cleaning solution backwards through the injector with some scrap hose. Also a cheap ultrasonic cleaner can help out but IMO they still need to be backflushed.

[Derek C.]

Might also check injector resistance and voltage to the injectors (use an analog voltmeter or a digital that reads fas and has a memory for peak voltage and see if it jumps, or jump a 12v LED across the connector terminals and look for pulsing). Seems odd to me that all 4 of them would be 100% blocked but not out of the question.

[porschedavid]

Hi Derek
Could you explain a bit more how to check them.Thanks

[Derek C.]

Here is a nice guide on checking injector resistance and voltage.

https://www.yourmechanic.com/article/how-to-ensure-fuel-injectors-are-receiving-the-correct-voltage-by-spencer-cates

[DannoXYZ]

Originally Posted by porschedavid

1989 PORSCHE 944 2.7
Turns over but wont start no fuel getting to plugs
Replaced fuel regulator,fuel pump.Checked injectors wires with noid lights all ok.
bypassed dme relay.
Still no fuel getting to plugs.

So you are getting injector-pulses as indicated by noid-light flashing when cranking?

What did you measure for fuel-pressure?

[porschedavid]

Yes i am getting injector-pulses while cranking

[porschedavid]

Just got injectors back from test and cleaned,still dont start,any ideas

[944 Ecology]

Are you sure it's a fuel problem. Redo the test with the bottles. Check the fuel rail pressure with a gauge.

Do you get a tach bounce while cranking?

[Jfrahm]

A noid light might show weak pulses but injectors need a pretty good zap to lift against fuel pressure. They should make a clacking sound when cranking. You can tickle them with some wires to see if they will clack, do not keep power on them, just tap the wires to the terminals. If you do this while the car is cranking, or just before, the car might catch.

[DannoXYZ]

You need to do testing to arrive at numbers and then compare those numbers to what's listed in FSM to really determine if part is bad or good. SO many people have swapped out perfectly-working parts for brand-new perfectly-working parts and nothing changes. Because those parts were working perfectly fine beforehand.

People have replaced with brand-new:

- fuel-pump
- fuel-hose
- fuel-filter
- fuel hard-lines under car
- fuel-rail
- fuel-pressure dampener
- FPR
- fuel-injectors
- speed/ref-sensors
- DME
- DME-relay
- AFM
- ignition-switch

When actual problem turned out to be short in injector harness or clog in fuel-line. At least you'll have a tonne of spares you won't need for next 10-years. Remember, every single part has an associated testing number given to it in FSM. Don't toss/replace part until you've confirmed it's bad by measuring it. So... here are some measurements and numbers you can make and your problems will jump out immediately.

1. what is battery-voltage at rest?

2. What is battery-voltage when cranking?

3. disconnect all injector connectors. With key ON (no cranking), measure voltage at every terminal of each injector connector (use battery-neg/chassis for ground of voltmeter):
- #1 connector, terminal #1
- #1 connector, terminal #2
- #2 connector, terminal #1,
- #2 connector, terminal #2, etc...
8 measurements total. What are these voltages?

4. Remove return fuel-line from FPR. Attach short section (maybe 3-4ft) of hose to FPR-drain and aim into bucket. Crank engine, do you get fuel in bucket?

5. Re-install FPR-line and measure actual fuel-pressure in fuel-rail when cranking. What is this pressure?