Hi Guys, Original question Hi Guys, its probably somewhere on here, but have had no luck searching.Does anybody know the Specs for original Merc Fuel pump (cool Fuel) for 2001 MAG MPI Horizon (454)
im after GPH mainly and at what pressure.
I will try to be more clear about why and what is happening. The reason i asked was after rebuilding engines (twins 454s) Originals2001 MAG MPI Horizon (454) with all new Holley EFI ecu's, Smart coils, Cam sync, crank sensor Hall effect. Approx 550-600 HP
Using original single centre fuel rail, coming in at front and exiting at rear to Turbo smart reg and then return to tank. Powering the fuel rail is a Pierburg 360 LPH @ 3 Bar External Fuel Pump. With all new 8an SS braided fuel line.
The pump location is similar to original position of the Cool fuel setup except on stringer not engine (easier to get at).
So my issue is - they were up n running fine idle really nice, base fuel set up on the careful side, but after running for only 20 mins at 3200 i noticed some serious blow by!!!! After returning -pulled upper stuff off then heads and hello - Pistons 5-6-7-8 Mainly 7-8 melting top thin edge.
After 2 weeks of debating the cause I'm at fuel starvation as both engines where the same problem at same pistons. And because the problem was so selective i believe fuel starvation over any advanced timing problem.
Both engines - same problem. I have now put new slugs in, rings bearings etc... ready to go but - i want to be convinced that i know what caused this... Hence why original thread asked for specs on original fuel pumps as they may have had better lifting capacity then my new ones.
When problem occurred pressure was reading 46 psi this was at sensor input on regulator.
I think Artic friends has been here before!! any input much appreciated.....before i try again....

Injectors ? I finished a 454 this spring that had burnt up one piston. I insisted that the customer have the injectors cleaned / checked and lo and behold the one for the bad cylinder was bad.

Hi Thanks for your input, all injectors where serviced before putting them back in and they where fine... Also both engines wouldn't be exactly the same in the same place if it was injectors it would be more sporadic.

The stock pump is a 190LPh, fuel pressure is 38 to 41 lbs at wot, about 34 to 37 lbs under vacuum. What was your target afr at tailpipes, this is VERY important. what injectors, what was timing at 3000, 3200, what kinda map/kpa or vacuum are you under at that point? You have modded stock MPI intakes? whats been done to them, stock throttle bodys? You have to work pretty hard to get a 454 to 600 hp with a mpi, what compression, what octane fuel?

Plus what pistons, Ive ran even srp 4032s with boost with no issues but Icon, and others are very fragile

Hi Arctic, the hp is only a guess i am probably way out!!!! Maybe its 400 - 450 HP - Was never after major HP just reliability -Pistons are ARP 212135
You did a Simulator check with my setup some time ago - but i dont remember the HP
i originally rebuilt with these same SRP pistons - bore etc but all stock gear (merc) including Injectors and fuel pump.- With no problems to pistons.
The only differences now are Holley hp ecu - O2 sensor - smart coils- cam sync - Crank sensor Hall effect and new fuel lines and pumps. Still using stock intake - stock throttle bodies.
AFR target was 14 from memory
Timing was 34 deg at 3200 (pretty sure)
Still using original injectors as EFI place here said they where fine after the service for my setup????
I dont remember the map/kpa at the time of the problem!!!!!
I only use Premium unleaded here in OZ and Compression is approx 9.5:1

If you were at 90 map/3.3" vacuum at 14-1 w 34 degrees at 3200, you were too lean, theres no where in a boat tune other than a dead idel where I would ever target anything with a 14 in front of it and that would only be if it liked it. I recently commented on a post where guy was asking about target afrs, and he remarked 'too much information isnt good either', I think he was referring to my countless post where I do everything I can to make sure people under stand tail pipe afr and the hottest cyl afr are NOT one and the same, I often see 1.5 to 2 points in each direction in areas of a tune so if you were truly at 14.0 tailpipe, you could have had cylinders as lean as 15.5, 16-1.
Now, for it to melt both 7 and 8 in each engine is kinda strange as those cylinders arent typically the lean ones on a mpi intake but then again, maybe at the throttle setting you were at they were, Smitty

Throttle setting ? help me here! what do you mean?
What if your correct with above and my AFR is high and i have slightly less fuel getting to those rear pistons with the higher AFR (14) would that maybe cause just the rear pistons to be leaner and not cooling the same as others? hence the melting????

Smitty, I was the one that said sometimes too little info is as bad as too much info. it was not a dig at you or all the great info you post, I have learned a lot with what you put out there. it was more that with too much info sometimes people get lost in it all and wind up overlooking simple things. please keep up the great work.

Smitty, do you have the ability to look at Holley base calibrations and settings? if so could send it to you and get you to check it for me, maybe i should go safe side and rich and then keep adjusting (reading plugs!)
Would you have a suggestion on where i should have my target AFR set at. By reading the info you sent im thinking say 12- 12.5 maybe????