Hard to start 502 mpi
06-23-2018, 01:37 PM
#1
Hard to start 502 mpi
97 502 mpi only 50ish hours. Will start right up when cold or has sat, seems to run fine until you shut it off. Will need full throttke and lots of cranking to fire...Has new F.P.R. positive lead on vst pump gets hot! Fuel pressure is 35ish after key is on, drops when revved up to 25 psi. Now shut it off wait 2 or 3 min and no start ..plugs are dry... Will not start with starting fluid at all?? Vst screen is clean boat panes fine and pulls fine up so not acting like fuel pressure issue when running. Also has a fuel cooler i assumed previous owner added.. I would say fuel pump is bad but no start with starting fluid confused me any help is appreciated
06-29-2018, 05:04 PM
#3
Registered
iTrader: (1)
97 502 mpi only 50ish hours. Will start right up when cold or has sat, seems to run fine until you shut it off. Will need full throttke and lots of cranking to fire...Has new F.P.R. positive lead on vst pump gets hot! Fuel pressure is 35ish after key is on, drops when revved up to 25 psi. Now shut it off wait 2 or 3 min and no start ..plugs are dry... Will not start with starting fluid at all?? Vst screen is clean boat panes fine and pulls fine up so not acting like fuel pressure issue when running. Also has a fuel cooler i assumed previous owner added.. I would say fuel pump is bad but no start with starting fluid confused me any help is appreciated
06-29-2018, 05:36 PM
#4
Fuel pressure @ 36ish psi, the pump is new, the F.P.R. is new , i also threw a ignition module in it as well. No fuel leaking into plenum from vst line or from manual pump vent line.
06-29-2018, 05:44 PM
#5
Registered
iTrader: (1)
just checked your history real quick - like Dejavu..you and me. LOL.
96 mpi mefi 1 no fuel pump or beep
======================
You have a see through spark tester to see how strong spark is at this point of no start ?
Use a scanner to check live data while no start ?
96 mpi mefi 1 no fuel pump or beep
======================
You have a see through spark tester to see how strong spark is at this point of no start ?
Use a scanner to check live data while no start ?
06-29-2018, 06:02 PM
#6
I only verified spark by eye not a spark tester. I only have automotive scanner, no access to a compatible scanner all the shops want me to book an appt. as they are busy. I wish i had a techmate or merc scan tool. I have also cleaned the IAC and throttlebody
08-27-2018, 09:00 AM
#8
Hi yes I have resolved the issue, after ruling everything else out a leakdown revealed bad intake valves. When my fuel pump was weak it leaned out motor and tuliped some intake valves. And I guess it would push the air fuel mixture into plenum and in turn flood the engine giving no start condition
08-28-2018, 12:59 PM
#9
Charter Member#157
Charter Member
Join Date: Oct 2000
Location: Minneapolis, Mn, Usa
Posts: 1,859
Likes: 0
Received 3 Likes
on
3 Posts
I would go after the IAC solenoid!
Same issue here I had and found the IAC was not working properly.
$30 @ Auto zone and runs like new.
Scanner will tell you a lot, find one and see what it is telling you.
Same issue here I had and found the IAC was not working properly.
$30 @ Auto zone and runs like new.
Scanner will tell you a lot, find one and see what it is telling you.
__________________
This Cat is trying to keep up with the Big Dogs
This Cat is trying to keep up with the Big Dogs
