Mercruiser Injectors Not Injecting

[pwskicat]

1995 Mercruiser 5.7L Magnum EFI (TBI) Tournament Ski
Ser. # 0F562552

This boat ran great all last season and was put to bed in October with zero problems. De-winterized it today and no start. Fuel pump is pumping but injectors are not spraying. This is the TBI system, not the MPI, with two injectors mounted on a throttle body that's sitting on the intake manifold where the carb would usually be. I'll be dragging out the shop manual. Any trouble shooting tips appreciated.

Many thanks for your help, PW

 

[pwskicat]

Checked the following:
• Engine cranks but not trying to run
• Sprayed starting fluid down the throttle body. Zero response. No kicking over, just cranking.
• Kill switch with lanyard installed is sending power to the engine (or at least the fuel pump)
* Fuel pressure OK
* Injectors not spraying

So no fuel and no spark. It seems like electric systems after the fuel pump are shut down. This engine has the MeFi-1 ECU, which has a 50A breaker. Is there a way to test this breaker, or would the engine not even crank of it was tripped? I've tried pushing it in to reset, but the switch doesn't go in or click. There is also an unmarked reset button on the dash. It's the one on the far right of the photo with no switch above it. Anybody know what that might be?

Thanks, PW

 

[Dieter]

Checked the following:
• Engine cranks but not trying to run
• Sprayed starting fluid down the throttle body. Zero response. No kicking over, just cranking.
• Kill switch with lanyard installed is sending power to the engine (or at least the fuel pump)
* Fuel pressure OK
* Injectors not spraying

So no fuel and no spark. It seems like electric systems after the fuel pump are shut down. This engine has the MeFi-1 ECU, which has a 50A breaker. Is there a way to test this breaker, or would the engine not even crank of it was tripped? I've tried pushing it in to reset, but the switch doesn't go in or click. There is also an unmarked reset button on the dash. It's the one on the far right of the photo with no switch above it. Anybody know what that might be?

Thanks, PW

If 50 a was tripped you would have nothing at the dash and would not crank. You can always test to see if you have 12 v on both terminals . If it were tripped you would have 12 von the upstream side and nothing down stream.

Do you have a wiring diagram for this engine ?

 

[pwskicat]

If 50 a was tripped you would have nothing at the dash and would not crank. You can always test to see if you have 12 v on both terminals . If it were tripped you would have 12 von the upstream side and nothing down stream.

Do you have a wiring diagram for this engine ?

Thanks for your reply. Six years ago, this engine wouldn't run at WOT because the Vapor Separator Tank (VST) had been ripped out of the fuel system by a previous owner. You helped me develop a work around. It's been running great ever since. So that component has been replaced by a high-pressure fuel pump. I hope the attachments will do. I have the have the complete shop manual. So if u need more pages just ask. In the wiring harness schematic check out #16. I have to locate that fuse to see if it needs to be replaced.

 

[makomark]

I'd start with the pickup coil in the distributor...if it has failed, you won't get any spark while cranking...no reference signal will inhibit the ECM from pulsing the injectors....

If the coil is ok, the electronics inside the distributor module would be next on the list....

on the mystery breaker, best thing is to dive in and start tracing wires...highly likely to be hull mfg specific....

 

[pwskicat]

I'd start with the pickup coil in the distributor...if it has failed, you won't get any spark while cranking...no reference signal will inhibit the ECM from pulsing the injectors....

If the coil is ok, the electronics inside the distributor module would be next on the list....

on the mystery breaker, best thing is to dive in and start tracing wires...highly likely to be hull mfg specific....

Thanks for your replyOther than replacing the distributor cap and rotor, I have no experience with distributors. How do I test the pickup coil? I have a multimeter, but nothing else.

 

[Dieter]

Thanks for your replyOther than replacing the distributor cap and rotor, I have no experience with distributors. How do I test the pickup coil? I have a multimeter, but nothing else.

Looks like from the drawing you have a delco EST not a Thunderbolt ?

This video I think covers it although may not be the best video, If it is EST I believe the distributor needs to come out, gear popped off and dist shaft pulled out of body to get coil out below.

 

[Dieter]

Thanks for your replyOther than replacing the distributor cap and rotor, I have no experience with distributors. How do I test the pickup coil? I have a multimeter, but nothing else.

Tryed to add this but it only lets you edit for 5 min...

13 thru 17 on your first drawing seem to be the relays and fuses that power your ecu, fuel pump, ignition, and injectors. Would start there also make sure you are getting a start/run 12 from the engine harness. Also I think 19 is from man overboard/kill switch possible you could be loosing the 12 v there between the cannon plug => engine harness => this injection system harness.

Also note the drawing you have is for an alpha drive but assume you are an inboard? just be aware some of the stuff like shift interrupt will be jumpered or not there on your set up. Basically there may be differences

 

[makomark]

Thanks for your replyOther than replacing the distributor cap and rotor, I have no experience with distributors. How do I test the pickup coil? I have a multimeter, but nothing else.

this is from the next release of the factory service data:
Testing Pickup Coil
1. Connect an ohmmeter to either pickup coil lead and the housing. If the reading is NOT
infinite, replace the pickup coil.
2. Connect an ohmmeter to both pickup coil leads. Flex the leads by hand at the coil and
the connector to locate any intermittent opens. The ohmmeter should read a constant
unchanging value in the 500-1500ohm range. If NOT, replace the pickup coil.

you can access the pickup coil's leads from the connector that mates to the ignition module.And Dieter is correct about replacing the pickup coil...

 

[pwskicat]

Looks like from the drawing you have a delco EST not a Thunderbolt ?

This video I think covers it although may not be the best video, If it is EST I believe the distributor needs to come out, gear popped off and dist shaft pulled out of body to get coil out below.

Thanks! I sent the only schematics I could find that were marked "EFI Throttle Body". All the others were for carb or MPI systems. Input to and output from the lanyard kill switch are 12.31V. I checked the fuses I referred to on the wiring harness and they are intact. Coil input from the wiring harness is 12.31. Coil output at rest is 12.31V, cranking output is 8.6V. Bad coil? To get non-cranking and cranking voltages, I put the multimeter positive lead on the post that connects the cable from the coil to the distributor cap and grounded the negative lead on the engine. The distributor is original to the boat and it looks like the control module is rusted in place, and I'm not sure if have the tools/skills to rebuild it anyway. I have found distributors priced from $335 (aftermarket) to $510 (Delco). Hope I don't have to go there. Just found out my ski buddy's dad knows an old school mechanic who might be able to help. He might come over tomorrow. I'll keep you guys posted and thanks again.

 

[pwskicat]

this is from the next release of the factory service data:
Testing Pickup Coil
1. Connect an ohmmeter to either pickup coil lead and the housing. If the reading is NOT
infinite, replace the pickup coil.
2. Connect an ohmmeter to both pickup coil leads. Flex the leads by hand at the coil and
the connector to locate any intermittent opens. The ohmmeter should read a constant
unchanging value in the 500-1500ohm range. If NOT, replace the pickup coil.

you can access the pickup coil's leads from the connector that mates to the ignition module.And Dieter is correct about replacing the pickup coil...

Thanks! Input to and output from the lanyard kill switch are 12.31V. I checked the fuses I referred to on the wiring harness and they are intact. Coil input from the wiring harness is 12.31. Coil output at rest is 12.31V, cranking output is 8.6V. Bad coil? To get non-cranking and cranking voltages, I put the multimeter positive lead on the post that connects the cable from the coil to the distributor cap and grounded the negative lead on the engine. The distributor is original to the boat, and I'm not sure if have the tools/skills to rebuild it anyway. I have found distributors priced from $335 (aftermarket) to $510 (Delco). Hope I don't have to go there. Just found out my ski buddy's dad knows an old school mechanic who might be able to help. He might come over tomorrow. Note: To access the pickup coil leads, I have to remove the module. To do so, I have to pull the screws for which a 5mm or 3/16 socket is too small and a 6mm or 1/4 is too big. Any tips? I'll keep you guys posted and thanks again.

 

[makomark]

if the mechanic is visiting soon, I'd defer to him...I don't remember having any issues with the screw heads with the last few that I've done...

Ignition wrenches may be one option....a good set of vice-grips another...worst case, you should be able to drill the heads off and then get replacements...

You can get a new distributor much cheaper that what you found...

 

[pwskicat]

if the mechanic is visiting soon, I'd defer to him...I don't remember having any issues with the screw heads with the last few that I've done...

Ignition wrenches may be one option....a good set of vice-grips another...worst case, you should be able to drill the heads off and then get replacements...

You can get a new distributor cap and much cheaper that what you found...

I've seen cheaper but when the one-star ratings are more than 10% of the reviews and there are lots of complaints about cheap construction, I usually write them off. Please recommend your sources and I'll check them out. Thanks!

 

[makomark]

look for the PM/conversation...

 

[Dieter]

Delco Distributor - 5.0L, 5.7L

OEM GM Delco distributor - 5.0L, 5.7L J117Compatible with the following distributors: Volvo Penta 5.0L #3857449 Volvo Penta 5.7L #3861987 Sierra #18-5484-1

www.michiganmotorz.com

Would do some more troubleshooting before getting parts cannon loaded. Certainly corrosion on connections is not going to help maybe a smaller 12 pt socket will fit the nuts. Or needle nose vice grip but they may break if rusted in

 

[jimn]

Look on the distributor for a part number.

I doubt the engine has crank sensors, so you need to find out if the distributor is outputting RPM to the ECM- the IC module is in the distributor and that could be the source of the problem, too- it's where the harnesses plug in. If you can have that tested, do it.

The Purple/white wire is Ref-Hi, which presents RPM info to the ECM- DO NOT pierce the insulation but you should check this wire by setting a multimeter to DC volts, then crank the engine. If you see 1-2VDC, it could be OK but if you see no voltage, the IC module or pickup is bad but make sure to follow the diagram when you check the other wires for Voltage (with the harnesses unplugged). You would beed to back-probe the terminals in order to test for voltage while cranking- go to a craft store and buy some T-pins (if you know someone who sews clothing, they might have these).

Does your engine have a lot of corrosion and standing moisture when you open the engine cover at the beginning of the season? If so, it's advisable to place a block under the engine cover, to allow air circulation.

 

[pwskicat]

The old-school mechanic came by this morning. We ran thru all the previous tests suggested by y'all, plus, he had a spark tester light, which is much easier to use than a multimeter with probes. He put it on a spark plug and cranked the engine. No light. Same test between the coil and distributor: same results. He marked the distributor position, pulled it and took it back to his shop to remove the control module and test the pickup coil. Hoping to hear from him in the next few days. Thanks again for all your help.

 

[pwskicat]

Right after I posted above, the mechanic called. He'd had a distributor that he knew was good at the shop and wanted to come by and see if it would solve the problem. My boat is still on the trailer and I had the fake-a-lake hooked up in case we got lucky. He put his distributor in and the engine started on the first crank! We let it run for awhile and It seems all good. The final test will be on the lake this weekend. I couldn't launch it when it wasn't running because my dock is 1/4-mile away from the ramp. The mechanic is somebody I'd heard about a lot because he's a family friend of the guys I ski with. One of them said can we bring him out to ski, and I said of course. I offered to pay him for his time and the distributor. He said "just take me skiing." Keeping my fingers crossed that we solved the problem, with your help of course.

 

[jimn]

Right after I posted above, the mechanic called. He'd had a distributor that he knew was good at the shop and wanted to come by and see if it would solve the problem. My boat is still on the trailer and I had the fake-a-lake hooked up in case we got lucky. He put his distributor in and the engine started on the first crank! We let it run for awhile and It seems all good. The final test will be on the lake this weekend. I couldn't launch it when it wasn't running because my dock is 1/4-mile away from the ramp. The mechanic is somebody I'd heard about a lot because he's a family friend of the guys I ski with. One of them said can we bring him out to ski, and I said of course. I offered to pay him for his time and the distributor. He said "just take me skiing." Keeping my fingers crossed that we solved the problem, with your help of course.

Did anyone test the Ignition Control module? That's probably the only thing that would have prevented it starting and I haven't seen anything that indicates it was tested. IC modules can and do fail and it's an easy part to test and replace.

 

[pwskicat]

I'd start with the pickup coil in the distributor...if it has failed, you won't get any spark while cranking...no reference signal will inhibit the ECM from pulsing the injectors....

If the coil is ok, the electronics inside the distributor module would be next on the list....

on the mystery breaker, best thing is to dive in and start tracing wires...highly likely to be hull mfg specific....

Ding Ding Ding! Your diagnosis was spot on! Scroll to the end of the thread to see how it worked out.

Did anyone test the Ignition Control module? That's probably the only thing that would have prevented it starting and I haven't seen anything that indicates it was tested. IC modules can and do fail and it's an easy part to test and replace.

If by the IC you mean the connector at the bottom of the distributor under the cap that has two connectors on the outside and hooks up to the pickup coil on the inside, no. In an earlier post, I described how this device was not going to come out because of the rusty sheet metal screws that held it in place. I any event, My boat is running and it didn't cost a dime. Pretty sure that has to be the best of all outcomes.

 

[jimn]

If by the IC you mean the connector at the bottom of the distributor under the cap that has two connectors on the outside and hooks up to the pickup coil on the inside, no. In an earlier post, I described how this device was not going to come out because of the rusty sheet metal screws that held it in place. I any event, My boat is running and it didn't cost a dime. Pretty sure that has to be the best of all outcomes.

Yes- that part is what the ECM controls, to advance/retard timing and trigger spark when the ECM receives RPM info.

I have heard of those rusty screws being removed, but it's tricky.

Glad to see a good outcome but I was asking as a matter of actually troubleshooting the problem.

BTW- that module grounds through the distributor base so if this happens again, attach a test lead between the base plate and a good ground on the block to see if it will run.