Hey HST4ME or anybody Mallory 4110M fuel pump

[stingray11]

Been running these pumps for many years. They have a factory setting of 7 PSI and are adjustable via allen key on the pump housing. I also run fuel pressure gauges in the dash that are manual fed with SS braided hose. Twin OMC motors so last time out left pump went to 12-14 psi from set 6psi after several mile run at 4000 RPM. Soon as I idle down back to 6 psi. Any body have this happen or thoughts.

 

[HST4ME]

Hmm a buddy is having a similar problem with a holley pump. Pull it apart and look at the bypass.

 

[Flying_Lavey]

Hmm a buddy is having a similar problem with a holley pump. Pull it apart and look at the bypass.

Since we are talking about fuel pumps.......

I know it is debated and there are 2 different schools of thought on the subject but, what flow would be needed for a 2.4L Merc that likes to rev pretty high? We'll say 7k rpm for some cushion.

 

[stingray11]

Since we are talking about fuel pumps.......

I know it is debated and there are 2 different schools of thought on the subject but, what flow would be needed for a 2.4L Merc that likes to rev pretty high? We'll say 7k rpm for some cushion.

If it's a carbureted motor a 110 gph would be plenty at 6.5 psi. Most v6 2 stroke use around 28 gph at full throttle

 

[Flying_Lavey]

If it's a carbureted motor a 110 gph would be plenty at 6.5 psi. Most v6 2 stroke use around 28 gph at full throttle

110 is a MASSIVE difference over the 28. But since I dont have a rev limiter and frequently spin it up over 6k (for short bursts right now, but I would like to go longer) Im assuming the 28 wouldnt be sufficient for that level of RPM. Would 50 be enough and still have some cushion? Seems like 110 may be a bit too much pump that the little stator woulcnt be able to overcome that draw.

 

[stingray11]

110 is a MASSIVE difference over the 28. But since I dont have a rev limiter and frequently spin it up over 6k (for short bursts right now, but I would like to go longer) Im assuming the 28 wouldnt be sufficient for that level of RPM. Would 50 be enough and still have some cushion? Seems like 110 may be a bit too much pump that the little stator woulcnt be able to overcome that draw.

I have been running 110's for 30+ years and my stators are only 10 amp and put out 0 Amps at Idle with no problems. All you have to do is put a fuel pressure gauge in the dash and see if it can keep up. I would highly recommend it, With out it you have no idea when the pump is going bad, and they all go bad at some point! And then your motor goes BOOM.

 

[Flying_Lavey]

I have been running 110's for 30+ years and my stators are only 10 amp and put out 0 Amps at Idle with no problems. All you have to do is put a fuel pressure gauge in the dash and see if it can keep up. I would highly recommend it, With out it you have no idea when the pump is going bad, and they all go bad at some point! And then your motor goes BOOM. View attachment 1381244

What motors do you run? I really don;t know what the amp output of my stator is, I just know its very low and I constantly have to charge the battery if I use the stereo much at all.

 

[stingray11]

What motors do you run? I really don;t know what the amp output of my stator is, I just know its very low and I constantly have to charge the battery if I use the stereo much at all.

I run 2.6 XP modified Evinrudes,pretty sure 2.4 Merc uses a 16 amp stator. I run ionic lithum red cranking batteries and they never go below 96% and never need to charge them. With the Bluetooth app I can see amp draw and amp output on my phone when running. They are only 14.6 lbs.

 

[stingray11]

Here is some pics of the app. This is running at about 4000 rpm,you can see it is charging the battery with 7 amps.

 

[stingray11]

 

[stingray11]

Ok I found out why my fuel pump was putting out high fuel pressure all the sudden. Lithium ion battery, when running the battery and it got fully charged and the battery management system shut the battery off and the voltage then went into my elect harness. Yea I finally noticed volt meter showing 16 volts and that made fuel pump run faster than it should and the pressure went up. Other problems, burnt up 3 tachs too. Water temp gauge may have taken a hit too. If your motor only has a rectifier and not a voltage regulator do not run a lithium ion battery. Stb motor has voltage regulator so that worked just fine. Some of the problem stem from my twin engine boat has fuel gauge and volt gauge with a switch to go from left to right so just happened to switch to left and that is when it hit me, 16 volts is way to much, Flooded batteries can absorb voltage even when fully charged. I since installed a regulated rectifier from CDI to tame down the voltage from left motor. It's got 1978 ignition system and electrics. So back to flooded batteries for starters. So I have 2 Ionic red starting batteries I will sell at a good price, 1400 cca and 14.5 lbs. $200each if anybody interested.