Mercruiser 3.0 Fuel Issues

[cubajorge_2008]

With the fuel regulator 5psi without it 9psi

But then again is do to missing the 0.25 gasket spacer. Which i will receive tuesday or wednesday. My main concern is why the fuel line from tank to pump wont stay full of gas. The anti syphone fitting is new and in place

 

[alldodge]

But then again is do to missing the 0.25 gasket spacer. Which i will receive tuesday or wednesday. My main concern is why the fuel line from tank to pump wont stay full of gas. The anti syphone fitting is new and in place

Might just be the pump, but need to verify first.
This is why every thread needs to start with a motor serial number

 

[cubajorge_2008]

Might just be the pump, but need to verify first.
This is why every thread needs to start with a motor serial number

Motor serial D851715

 

[alldodge]

List a Carter fuel pump and should output 5.25 to 6.25 psi
With it's output at 9, then something is wrong with the pump. It also doesn't use 2 gaskets

 

[cubajorge_2008]

List a Carter fuel pump and should output 5.25 to 6.25 psi
With it's output at 9, then something is wrong with the pump. It also doesn't use 2 gaskets

The gasket (spacer) 0.25 thick arrived. I will test it out and see if that fix the problem

 

[cubajorge_2008]

Guys the problem was fixed with the pump doing 9psi. Now it does 6psi adding the gasket (spacer) 0.25. I also added a fuel water separetor. And temove the clear filter. Now i want to fix the other issue i have. At start up when the engine is idling it smokes i will post a new threat. Thanks guys for helping me on this one

 

[Scott06]

Guys the problem was fixed with the pump doing 9psi. Now it does 6psi adding the gasket (spacer) 0.25. I also added a fuel water separetor. And temove the clear filter. Now i want to fix the other issue i have. At start up when the engine is idling it smokes i will post a new threat. Thanks guys for helping me on this one

Probably choke idle mix or compression….

 

[alldodge]

Probably choke idle mix or compression….

Agree

 

[cubajorge_2008]

Agree

Choke idle mix uhmmm should i post a new thread or keep going here? If so how do you fix the choke idle mix

 

[alldodge]

Choke idle mix uhmmm should i post a new thread or keep going here? If so how do you fix the choke idle mix

No need for new thread unless you want to get maybe more input, and nothing wrong with more input

If this happens when the motor is cold but not when warmed up, then its the choke, and it needs adjusted

If it happens all the time at low idle, then its mixer screws and/or float settings

 

[Scott06]

Choke idle mix uhmmm should i post a new thread or keep going here? If so how do you fix the choke idle mix

Its really three separate tune up functions

get factory manual

set choke per factory manual make sure choke doesn’t hang up and fully opens may be too closed and making it too rich thus black smoke soot on transom.
set idle mix screw, idle speed screw, timing per factory manual. If idle mix screw doesn’t stall engine when full in lean then needle and seat, float may need work.
test compression. New engine is 150 psi compression if below 125 psi engine is showing wear smoke could be from oil via rings and valves seals. Initial smoke on start up that goes away can be from oil leak down via valves .

maybe someone can post the manual pages ill look for them

 

[cubajorge_2008]

No need for new thread unless you want to get maybe more input, and nothing wrong with more input

If this happens when the motor is cold but not when warmed up, then its the choke, and it needs adjusted

If it happens all the time at low idle, then its mixer screws and/or float settings

Only happens when cold

 

[Scott06]

Only happens when cold

Set the choke a tad leaner https://www.carburetor-blog.com/knowledge-base/mercarb-choke/

 

[cubajorge_2008]

Guys i think i figure out the issue. What can a bad pump rod adjustment do? Is way off. I will fix it tomorrow. The little thing has 3 holes and it is set on the middle one. And it is not on 29mm is more like 40 almost. I think Thats why the choke will not work properly and idle is always off.

 

[Grub54891]

Guys i think i figure out the issue. What can a bad pump rod adjustment do? Is way off. I will fix it tomorrow. The little thing has 3 holes and it is set on the middle one. And it is not on 29mm is more like 40 almost. I think Thats why the choke will not work properly and idle is always off.

if no one has messed with it, it should be correct. The pump rod pumps a squirt of fuel when you pump the throttle. Look at the holes and see if they are worn or look like it was in a different one before. Nothing I hate worse than someone moving/bending/ and messing with the linkage when they think they can fix it and don't know what they are doing.

 

[Scott06]

Guys i think i figure out the issue. What can a bad pump rod adjustment do? Is way off. I will fix it tomorrow. The little thing has 3 holes and it is set on the middle one. And it is not on 29mm is more like 40 almost. I think Thats why the choke will not work properly and idle is always off.

Post a picture, but i think That would only affect it if the accelerator pump was hung up and not letting throttle return .

 

[havoc_squad]

Guys the problem was fixed with the pump doing 9psi. Now it does 6psi adding the gasket (spacer) 0.25. I also added a fuel water separetor. And temove the clear filter. Now i want to fix the other issue i have. At start up when the engine is idling it smokes i will post a new threat. Thanks guys for helping me on this one

This is a common issue of people who do not know the subtle differences in gaskets used on that mechanical fuel pump model depending on the engine that it is installed in. I believe that pump used by the GM 3.0L inline 4 cylinder is shared between several GM V6 and V8 engines that are equipped for a mechanical fuel pump.

I had a boat service shop screw up a fuel pump replacement on a GM 3.0L because they weren't paying attention when they ordered parts.

Wasted a bunch of my time, I diagnosed and fixed the issue myself with some free help from a different service shop that I bought the fuel pressure tester fitting from.

This was way back in 2011 I think. Learned alot since then and did more of the work myself.