Choke or Cold Start 91 250?

What is used to start a cold 91 250? I think it is stuck in cold mode on the starboard engine.

Thanks

Re: Choke or Cold Start 91 250?

on each carb is a small solinoid.
the #6 fuel bowl supplies fuel to an electric fuel pump mounted low between the carb banks.
this pump runs anytime the key is on.
based on signals from the start circuit,the engine temp sensor the ECU determines how much extra fuel to add to ensure the correct fuel mix for cold start, warm up, rapid acceleration and rapid decell plus knock detect.
use the diagnostic test lamp, look for code 33, a defective stuck open T-stat can cause the ECU to add fuel as the temp sensor wont warm up.
a defective temp sensor can cause it as well, blown lift pump diaphrams, common on a 3.1L motor, can make it run pig rich as well.
just a note, running at high speed with a bad T-stat can blow #6 piston as the ECU will open all six solinoids cause it thinks the engine is cold and drain #6 fuel bowl causing a lean out on #6, its easy to spot cause when I pop the head parts of the piston crown at the ring land are missing.
but what are your running symptoms and why do you think its stuck in start mode ?

Re: Choke or Cold Start 91 250?

Thanks rodbolt. This is why:

engine doesn't kick down like the port

gas film on the water

uses more gas but equal oil

has compression and spark

new fuel pumps

Re: Choke or Cold Start 91 250?

I should add that the port heads on both engines feel a little hotter that the starboard heads but seem the same from motor to motor.

Also while the starboard engine is running there are little fuel droplets coming from the prop the whole time.

One the FMG starboard reads 3.5 gph at 6-7 rpm and port reads 1.5 gph at 6-7 rpm

Re: Choke or Cold Start 91 250?

normal problem with your symptoms indicte a blown fuel pump diphrm, the knock sensor the temp sensor or a solinoid or solinoid Oring is leaking.
if the ECU sees any sensor failure it locks the timing at 7*BTDC and idle speed stays about 1100.
can you get a copy of the tune up guide, LIT-18559-84-05 ?

Re: Choke or Cold Start 91 250?

Thanks rodbolt

It is idling at 700 but that doesnt mean someone didn't turn the idle down in the past. This engine has run like this since I got it.

The 3 fuel pumps are brand new. Have you ever seen a defective one out of the box?

I there is a leak would I see it or is it internal?

Where can I buy that tune up guide? I have the factory manual. Is it in there?

I'm thinking I might spring for a winky blinky.

Re: Choke or Cold Start 91 250?

I'm going to put new t-stats in tonight and see if that helps.

Re: Choke or Cold Start 91 250?

I pulled and old helicoil out of one of the holes. Now the real fun begins :0(

Re: Choke or Cold Start 91 250?

OK , I got the t-stats replaced but that didn't help.

Any ideas? Rodbolt?

Re: Choke or Cold Start 91 250?

your simply going to have to use the diagnostic test lamp, if you get a code one it eliminated a lot of checks.
check the ign timing, if there is a fault it will lock at 7* BTDC and idle speed will increase, normal idle timing is about 7* ATDC.
then you will have to double check all the linkage synchronazation, carefully and by the manual. its not for the faint of heart and even some techs have difficulty with it. also check the TPS reference voltage and output voltage.
at engine start up you will get a code 33, once warmed up the test lamp will display any codes in order from higest to lowest, code one being normal.
if you get a trouble code it will have to be corrected to look for any other codes. it will only display one at a time.

Re: Choke or Cold Start 91 250?

Thanks rodbolt. Now I need to find a winky blinky