Logo
FULL SITE MENU

Wrong elec fuel pump? 5.0 carb'd 40psi!

FstaRockr Burns

FstaRockr Burns

Regular Contributor
Little confused with the merc fuel pump part #s -

Had a carb flooding issue, rebuilt / same deal. Checked fuel pump pressure is 40 psi!!

SN not legible - but its a 2001 5.0 merc with a 2 barrel mercarb and elec pump setup -

Did someone put on the incorrect pump?

Pump on boat currently is:
861155-2
1740 A

Merc catalogues lists 861155A3 as the correct fuel pump.

Does the last digit indicate pressure? I thought it was the fuel fitting configuration -
 
Last edited:
FstaRockr Burns said:
Little confused with the merc fuel pump part #s -

Had a carb flooding issue, rebuilt / same deal. Checked fuel pump pressure is 40 psi!!

SN not legible - but its a 2001 5.0 merc with a 2 barrel mercarb and elec pump setup -

Did someone put on the incorrect pump?

Pump on boat currently is:
861155-2
1740 A

Merc catalogues lists 861155A3 as the correct fuel pump.

Does the last digit indicate pressure? I thought it was the fuel fitting configuration -
Click to expand...

Entirely possible someone ordered a high pressure (fuel injection) pump and installed it. Either way (if it is a low pressure pump) it has failed 40 psi is way too much for a carb you will flood. Get the correct low presusre pump and install it.
 
question is is 861155A2 a low or hi psi pump?


Merc catalogues lists 861155A3 as the correct fuel pump.. some sites reference the both pumps (A2 and A3) and same ??
 
FstaRockr Burns said:
question is is 861155A2 a low or hi psi pump?


Merc catalogues lists 861155A3 as the correct fuel pump.. some sites reference the both pumps (A2 and A3) and same ??
Click to expand...

861155A2 (as opposed to the slightly different number you gave off the pump) shows as low pressure pump. A3 superceeded A2 you can type the part numbers in the search box at top page here- http://www.marineengine.com/newparts/part_search.php?part_num=861155A2


I think these pumps are made by Airtex, you may be able to find the OE pump for much less. I belive the airtex number is E11003.

 
Listed as low pressure and as a low pressure boost pump but 40 psi is not a low pressure pump. You need no more than 6 psi
 
So I found a service bulletin stating the check ball can get stuck in the pump which drives psi up, and also the 3mm needle seat assembly can cause this. Merc released an updated needle seat kit for this issue.

"- 3 -97-8 1-599 MerCarb Flooding on 1990 and newer 3.0L, 3.0LX, Gen+V6 and Gen+V8 305/350 cid ModelsThis information applies only to the engines listed. If you get a complaint that the 2-bbl carburetor is flooding,do the following:On the V6 and V8 engines with electric fuel pumps, make sure that the pump is not putting out too high ofa fuel pressure. 10 psi (69 kPa) is the maximum pressure for these pumps. 30-40 psi (207-275 kPa) havebeen reported on some of these pumps. This high pressure is caused by a stuck check valve inside thefuel pump. The stuck check valve is caused by dispersant in today’s fuel within the USA, see Service Bulle-tin 98-5. To free this check valve up, plug the carburetor end of the fuel line with a Tee fitting. Install a 60psi (414 kPa) guage to the other port in the Tee fitting. Run the pump to ‘dead head’ it against the pluggedTee fitting. When the pressure drops to about 8 psi (55 kPa), the check valve has been freed up.On all engines, check the carburetor to make sure that it is not causing the flooding condition.If neither of these problems are causing the flooding, order the 2.5 mm Needle and Seat Kit from Quicksil-ver. The original needle and seat in the carb has a 3.0 mm ID hole in the seat. The 2.5 mm hole in the newseat gives the needle more area to seat against and allows less pressure through it.3302-804689 Needle and Seat Kit - 2.5 mm"
 
Bt Doctur said:
And how does one take apart this electric fuel pump ?
Click to expand...

According to the bulletin you dont, you just dead head it till the psi drops .. few taps with a plastic hammer prob helps. I might try that - honestly I dont know why merc doesnt make a 5psi pump for carbs. 10psi is way too much for most carbs anyway unless you are racing or doing some extreme stuff..

Now $30 for an "updated" needle seat assembly to bandaid the issue - wont be surprised if that doesnt really solve it..
 
Back
Top