4.3l mpi crank no start

[shane1230]

Hi all,
Hoping someone can point me in the right direction to start testing. I just replaced my boat battery w/1000mca. After the old battery wouldn't take a charge, it was about 10 years old. I left the boat key on for a week and went out to a dead battery, it was down to 8v and wouldn't take a charge. Now the boat cranks but doesn't start. Every now and again it will cough as it tries to start. When I turn the key on, the alarm beeps once and it now consistently takes 20 seconds before the fuel pump primes and it stays on along with a solid beep from alarm. Before it would prime 2-3 seconds and turn off right away and start relatively quickly.
4.3 mpi s/n 0m357557

 

[cyclops222]

I am not sure. But I think lots of stuff was overheated without water circulated by the running engine. Good Luck
Are you trying to start with that run down battery ?

 

[Scott06]

Hi all,
Hoping someone can point me in the right direction to start testing. I just replaced my boat battery w/1000mca. After the old battery wouldn't take a charge, it was about 10 years old. I left the boat key on for a week and went out to a dead battery, it was down to 8v and wouldn't take a charge. Now the boat cranks but doesn't start. Every now and again it will cough as it tries to start. When I turn the key on, the alarm beeps once and it now consistently takes 20 seconds before the fuel pump primes and it stays on along with a solid beep from alarm. Before it would prime 2-3 seconds and turn off right away and start relatively quickly.
4.3 mpi s/n 0m357557

Do you have spark? Take coil wire off and hold it close to ground while cranking. Need to determine if are missing fuel or spark

 

[shane1230]

I am not sure. But I think lots of stuff was overheated without water circulated by the running engine. Good Luck
Are you trying to start with that run down battery

No, brand new battery. Placed on the charger to be sure it was full before putting it to use.

 

[shane1230]

Do you have spark? Take coil wire off and hold it close to ground while cranking. Need to determine if are missing fuel or spark

I will have to test spark tomorrow. Pretty sure it's getting fuel, fuel rail pressure shows 43psi once pump kicks on.

 

[cyclops222]

I have a severe case of a lot of damaged parts on the engine. Good luck with the problems.

 

[Scott06]

I will have to test spark tomorrow. Pretty sure it's getting fuel, fuel rail pressure shows 43psi once pump kicks on.

Yes if you have 43 psi you should be good. One thing on the mpi engines the crab style dist cap is a known problem area . May not be your issue but migh5 be worth swapping out

 

[alldodge]

When I turn the key on, the alarm beeps once and it now consistently takes 20 seconds before the fuel pump primes and it stays on along with a solid beep from alarm.
4.3 mpi s/n 0m357557

Thanks for the SN, your have a 555 ECM

With the solid alarm the ECM is seeing either the drive lobe bottle low or overheat. Disconnect the lube bottle and the ECT sensor on the thermostat housing. The ECT will have 2 wires on it

 

[shane1230]

Thanks for the SN, your have a 555 ECM

With the solid alarm the ECM is seeing either the drive lobe bottle low or overheat. Disconnect the lube bottle and the ECT sensor on the thermostat housing. The ECT will have 2 wires on it

I disconnected the two wires to the lube bottle and the ect connector with no change. Also disconnected and reconnected other sensors that I could see with no luck either

 

[alldodge]

Might still be low voltage reading from corrosion.
Measure voltage at the key switch Red/Purple wire before and after start.

Check 5V circuit at either oil pressure sensor (Gray wire or 3 wire plug) to ground. I think you have a water pressure sensor on power steering cooler, and if so same measurement

 

[shane1230]

Might still be low voltage reading from corrosion.
Measure voltage at the key switch Red/Purple wire before and after start.

Check 5V circuit at either oil pressure sensor (Gray wire or 3 wire plug) to ground. I think you have a water pressure sensor on power steering cooler, and if so same measurement

all voltage checks appear good. getting 5 volts at sensors i could find. disconnecting sensors from power plug one at a time. still getting alarm after key off for reset. 12v at fuel pump and ignition switch. i attached an in-line spark tester to a plug. getting some spark, not sure if it's strong enough it's an orange flash.
what boggles me is the 20 second delay to energize fuel pump from ecm when key is turned on. as soon as ecm times out? fuel pump is constantly on with solid alarm. previously key on pump would prime for 2-3 seconds and turn off no alarm. is it plausible that the old battery took out the ICM?

 

[alldodge]

Might call Bob at OBD Diagnostics to see if he can test the ECM.
https://obd2allinone.com/

 

[alldodge]

Oh and should add, if you scanned the motor it should be able to tell you what the error is