Mercuiser 4.3EFI Wont start - how to troubleshoot the fuel system

[SandyBoat]

I have a 2001 4.3EFI (serial OMO98359) which won't start. The battery is fully charged, there is plenty of fresh fuel in the tank, spark from the spark leads but no sign of fuel at the injectors at the throttle body.

I can hear the fuel pump when the ignition is switched on as normal, the engine cranks fine, but no sign of life. I took the water separating fuel filter off and it was full of fuel. The fuel **** is on. I have looked in Service Manual 25 at the fuel system troubleshooting (5H) but that doesn't have a section on no starts.

Can anyone point me in the direction of a troubleshooting guide for this engine or have any other suggestions of what to start looking at?

TIA

 

[Bt Doctur]

double check the serial number , cant get a match. Try putting a shot glass of gasoline into the inlet to see if it will fire.Other than that are you positive its fuel and not water? There should be a schrader valve in the fuel rail. you can depress the pin to bleed the line when you hear the pump running.

 

[Fun Times]

To check the fuel pressure you'll need the fuel pressure tee tool merc part number 91-806901 along with an "EFI" fuel pressure gauge which you can obtain locally at an auto store. You're looking for 30 PSI.

Description: Tee can be installed between fuel line and TBI unit to measure fuel pump pressure. For EFI (TBI) throttle body models and on inlet side of VST on EFI / MPI models. Tee is used with 91-16850A1, A2, A3 or A7 Fuel Pressure Gauge. The Fuel Pressure Tee is included with the 91-881833A2 Fuel Pressure Gauge Kit .

http://www.ebay.com.au/itm/NIB-Fuel-...item1c4c2f7717

Though he shows the wrong size fitting, here is a visual of what you need to do. http://forums.iboats.com/forum/engin...ressure-on-tbi

 

[alldodge]

I have a 2001 4.3EFI (serial OMO98359) which won't start. The battery is fully charged, there is plenty of fresh fuel in the tank, spark from the spark leads but no sign of fuel at the injectors at the throttle body.

I can hear the fuel pump when the ignition is switched on as normal, the engine cranks fine, but no sign of life. I took the water separating fuel filter off and it was full of fuel. The fuel **** is on. I have looked in Service Manual 25 at the fuel system troubleshooting (5H) but that doesn't have a section on no starts.

Can anyone point me in the direction of a troubleshooting guide for this engine or have any other suggestions of what to start looking at?

TIA

Here is the troubleshooting guide from my manual 25 , starts at page 1-C9
Edit: my mistake you said you do have spark

 

[alldodge]

Here is the troubleshooting guide from the same year small block V8

 

[SandyBoat]

Thanks for responses. I didn't realise the hard start troubleshooting is what I needed. I will go down to the boat tomorrow and follow the steps.

 

[floater212]

I had a similar problem 2yrs ago, it fired and died as soon as the key went to run. turned out to be the injectors where air locked, bled out schrader 4-5 times till air was all out, it fire right up and kept on running, fine ever since. double check fuel filters for air space.

 

[SandyBoat]

double check the serial number , cant get a match. Try putting a shot glass of gasoline into the inlet to see if it will fire.Other than that are you positive its fuel and not water? There should be a schrader valve in the fuel rail. you can depress the pin to bleed the line when you hear the pump running.

I've checked the serial number and it is correct, but I typed it wrong - the second O is in fact a zero - OM098359 . There is no Schrader that I could find, so it looks like I will need the tee tool that FunTimes linked to. Can anyone check that is the right part based on the engine number? I looked on the Mercruiser site but couldn't find it.

As I will have to disconnect the fuel line from the throttle body to fit the tee is it worth putting the end in a bottle and see if fuel comes out when I try and start the engine?

Thanks again for the replies.

 

[Fun Times]

I've checked the serial number and it is correct, but I typed it wrong - the second O is in fact a zero - OM098359.

Also the first O is actually a 0 as well but most of the computers that look up Mercrusiers serial numbers are programmed correct it to an 0. But it won't catch any other mistakes such as an O after 0M.... I knew that and already looked up your engine and it comes up an MERCRUISER 4.3L ALPHA EFI 2 PC 4.3L ALPHA EFI Serial No: 0M098359 Model No: 4231067N1 Parts Catalog No: 90-83498700. http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=834987+00

There is no Schrader that I could find, so it looks like I will need the tee tool that FunTimes linked to. Can anyone check that is the right part based on the engine number? I looked on the Mercruiser site but couldn't find it.

That tool won't be found in the parts catalog.... it's found in the service literature.

Being an EFI/throttle body, your engine model won't have the Schrader valve....MPI's offer the Schrader valve.

Yes it's the correct tool, http://www.bing.com/search?q=91-806...=-1&sk=&cvid=b8a1448ce9a5465d969c11d6a5844f74

As I will have to disconnect the fuel line from the throttle body to fit the tee is it worth putting the end in a bottle and see if fuel comes out when I try and start the engine? Thanks again for the replies.

If you do this you need to be very careful when you turn the key on because It will be very messy if the fuel pressure is high....Plus it won't be an accurate read if you think you see a lot of fuel flowing out and not actually get a pressure reading of actual fuel pressure as anything under say 15 psi the engine may not run at all. Again you need to be in the 30 psi range at key up and then have the vacuum hose to the fuel pressure regulator disconnected while the engine is running for a more accurate pressure reading.