MERC 95 350 TBI injectors not working
 

Hi guys,

I'm rebuilding a 350 merc with TBI fuel injected. When I manually squeeze some fuel in the manifold, she will fire up right away but will die after a couple of seconds because no fuel. Injectors are not squeezing any fuel at all.

With ignition on, voltage at the left injector is 0,64 V, right one 0,03 V which doesn't make any sense. Already changed both injectors (from spare engine), complete distributor , no luck.

How to test /solve this problem?

Anything to do with lanyard start/stop switch not connected?
I have the diacom software but with not a running engine, not much testing possibilities

What is your cranking fuel pressure?

No idea what fuel pressure is ... cannot test it...
fuel lines are full with fuel ... when loosing nut, fuel squeezes out with pressure... electrical fuel pump already replaced (was not working at all, internally blocked I suppose)

It might be a longshot but the ECM will cut out the fuel injectors while the engine is cranking if the throttle is held open. This is a feature used to clear out a flooded engine. If the TPS is malfunctioning then the computer might think the throttle is open and not injecting any fuel. Try starting the engine with the TPS unplugged or with a known good unit. If It starts but won't idle then replace the TPS.

GF?

Good idea... I tried it but no changes ...
What else to try?

Clean injectors?

Yes, think so, I already replaced 2 injectors from spare engine (which was running before cracked block (frozen)

How much voltage at injectors is needed? Can I test them manually with some source? 6V f.ex?

check fuel pressure with a gage, they wont put out any fuel if the pressure is low, it takes 9-15 pounds I think with throttle body inj. and also make sure your getting a good ground, ive seen a lot of guys bang there head against the wall only to have a ground off or loose.

Check to make sure the fuel pump runs for a few seconds each time you turn the ignition key to the run position. Checking the voltage at the fuel injectors might show you the issue but it won't help identify the cause. You either don't have any fuel pressure (or gas in the tank) or something is preventing the ECM from energizing the injectors.

Check to see if your tachometer needle moves at all while cranking, the ECM needs a tach signal to add fuel. Make sure all of the black ground wires that run to the stud on the bell housing are connected. The ECM and injector grounds all lead there.

Given that you don't have a fuel pressure guage, find the Schraeder valve on the fuel injector rail and push the pin to see if fuel is even getting to it.

Good luck,
GF?

DIY Code Reader
Materials needed:

One 12volt resistor type LED light - Standard LED nothing special make sure it is a 12 VOLT
One small paper clip cut in half

That’s it!

This home made code tool works every bit as well as the one I paid $50.00 for. It will work on most 1993 to 2000 marine EFI systems with the ten pin Data Link Connector. This includes MerCruiser, Volvo, Crusader, PCM, Indmar, and a few others.

How to hook it up:

1) Ignition key “OFF”

2) Remove the cap from the Data Link Connector (DLC)

3) Slide the LED into the female terminals of position E and F on the DLC, making sure that the positive side goes into terminal F and the negative side into terminal E. No damage will occur if you get it backwards, it just won't work.

4) Turn the ignition key to the “ON” position. The LED should come on steady.

5) Insert the half paper clip into terminals A and B – This puts the engine in “Service Mode” and codes will begin to flash on the LED. On 1996 and earlier engines you may hear the fuel pump come on. If not you should be able to hear the Idle Air Control (IAC) motor move. Use care in this step, do not insert in the wrong terminals or ECM damage could result! Look closely, the terminals are clearly marked.

6) Read codes by observing LED flashs. If the self diagnostic system is working it will flash code 12 – one flash, pause, two flashes, long pause – it will repeat three times. If other codes are present they will flash in order of lowest to highest. Continue to read codes until the code 12 sequence is repeated.

You can also be clear codes (by moving the throttle to 100% and back) and set base timing while in Service Mode.

If