454 mag mpi chuggles/stalls

[vroom ZOOM]

so again, that MAP is increasing for no reason. shouldn't be with the IAC closing... I'm still curious as to what the timing is doing

I will put my light on it tomorrow.

 

[nola mike]

I will put my light on it tomorrow.

can't you graph it with the diacom?
and did you ever unplug the IAC?

 

[Fun Times]

You mentioned a new long block and the previous engine had the same issue. Did the intake manifold come from the old engine to the 'new' long block? (sorry if that was already discussed)

This question on post 61 seemed to go unanswered...?
As in some reference, is item numbers 2 and 3 in place?, https://www.mercruiserparts.com/bam/subassemblydetail/37744147/28149300

*NEW OEM* 0810 Mercury Quicksilver Fitting 22-805691 | eBay

We kindly ask that you confirm the item fits your needs before purchasing.

www.ebay.com

Mercury Quicksilver OEM 19-854310 Plug | eBay

If we say the item works, then it was tested to the best of our ability.

www.ebay.com

Check the vacuum lines that connect to the fuel damper/regulator at the back of the fuel rail, port side of engine. There should be no fuel present in the line

That damper can fail and cause an overfueling/rich condition at idle. It will be evident by checking for fouled spark plugs

If this is indeed your cause, the damper is nla from merc and GM. In the past I've plugged the damper vacuum connection and the vacuum line at the damper to solve the issue

Also post 13 needs attention.... Is there gas in the vacuum line / coming out of the fuel regulator? See hose A / 46, https://www.mercruiserparts.com/bam/subassemblydetail/37744147/28149300

Also in one of the videos above, the flame arrestor (#38) appears extremely black and dirty, have you cleaned it? ran the engine with it off and/or another one when you swapped plenums? Hope the engine isn't starving for air.

One sensor wasn't physically mentioned as being swapped out and tried but I suspect it was tried with the swapped out plenum is of the MAP sensor itself.
Have you tried a new/another used MAP by itself? I saw you unplugged it, etc. but have you inspected the MAP seal too (Item number 20)? They become compromised.
This may sound dumb but in the past I had found 2 bad MAP sensors by accidentally putting/resting my forearm down on the top of the (454/502 MPI) map sensor while the engine was running and found the particular issue the engine was having as the weight changed the engines behavior to normal... Try touching the MAP sensor...

Try swapping item number 17 just because, https://www.mercruiserparts.com/bam/subassemblydetail/37744137/28149300

Engine temp is reaching 154 degrees minimum? I saw 132.8 in one of the posts above not answered.

Item number 18 in place, https://www.mercruiserparts.com/bam/subassemblydetail/37744139/28149300

 

[vroom ZOOM]

can't you graph it with the diacom?
and did you ever unplug the IAC?

Yes I can...


havent tried unplugging the iac but will try that today.

 

[vroom ZOOM]

This question on post 61 seemed to go unanswered...?
As in some reference, is item numbers 2 and 3 in place?, https://www.mercruiserparts.com/bam/subassemblydetail/37744147/28149300

*NEW OEM* 0810 Mercury Quicksilver Fitting 22-805691 | eBay

We kindly ask that you confirm the item fits your needs before purchasing.

www.ebay.com

Mercury Quicksilver OEM 19-854310 Plug | eBay

If we say the item works, then it was tested to the best of our ability.

www.ebay.com

Also post 13 needs attention.... Is there gas in the vacuum line / coming out of the fuel regulator? See hose A / 46, https://www.mercruiserparts.com/bam/subassemblydetail/37744147/28149300

Also in one of the videos above, the flame arrestor (#38) appears extremely black and dirty, have you cleaned it? ran the engine with it off and/or another one when you swapped plenums? Hope the engine isn't starving for air.

One sensor wasn't physically mentioned as being swapped out and tried but I suspect it was tried with the swapped out plenum is of the MAP sensor itself.
Have you tried a new/another used MAP by itself? I saw you unplugged it, etc. but have you inspected the MAP seal too (Item number 20)? They become compromised.
This may sound dumb but in the past I had found 2 bad MAP sensors by accidentally putting/resting my forearm down on the top of the (454/502 MPI) map sensor while the engine was running and found the particular issue the engine was having as the weight changed the engines behavior to normal... Try touching the MAP sensor...

Try swapping item number 17 just because, https://www.mercruiserparts.com/bam/subassemblydetail/37744137/28149300

Engine temp is reaching 154 degrees minimum? I saw 132.8 in one of the posts above not answered.

Item number 18 in place, https://www.mercruiserparts.com/bam/subassemblydetail/37744139/28149300

Yes, the intake came from the old engine, and that is the only part I have not tried moving from the other engine, aside from the transmission. I will move it over today.

As for parts 2 and 3 there isnt even a hole for them in the intake.
No fuel in the vacuum line to the regulator.
Flame arrestor wise, the other engine runs with either or. I tried swapping them to no avail. I can see light through both so they should pass enough air to idle. If they were restricted I would see a very high vacuum as the engine starves for air. definitely not the case here.

Tried a new oem GM map sensor and tried the one from the other engine. Also tried swapping the distributor jumper harness.

That little connector (#18), where does it go? I do not recall seeing one.