VetteSteve

I have been researching to find out how to determine the correct fuel pump for my marine engine. I found a formula for the fuel requirements on Holley.com but I do not know how the fuel pressure and volume are used in choosing the proper fuel pump. With all the knowledge on OSO, someone will know the correct answer! Thank you for your help.

In 2009 I had a 540 C.I. normally aspirated marine engine built by an engine dealer. After 19 hours the engine failed. In June of 2010 while running at WOT, 5600 rpm, cylinder #6 incurred a ½” hole in the dart aluminum cylinder head caused by detonation. Because of the hole went into the water jacket, water flow was lost and the engine over heated and the heat tabs melted. The engine required a rebuild.

I believe I have provided the pertinent information below but if any other info is required please let me know. Fuel used is always 93 octane.

The engine dealer installed parts: fuel pump was a Carter M61045, Carburetor is a Holly 1150, Compression Ratio: 9.490: 1, ignition timing at final advance is 34.0 degrees BTDC @ 4500 rpm. The dyno sheet provided by the builder states; peak torque at 4900 rpm – 611.4 HP - 654 torque – fuel pressure 4.967 Psi; peak HP at 5900 rpm – 670.3 HP – 595.5 torque – fuel pressure 5.009 Psi.

Rudy Dryden did the engine rebuild and installed a temporary fuel pressure gauge. After the rebuild WOT fuel pressure was fluctuating between 3.75 and 4 PSI. Rudy was not happy with the numbers so first he upgraded the original 502’s Mercruiser fuel lines and water/fuel separator. Then another test run provided the same fluctuating fuel pressure of 3.75 to 4 PSI. So after upgrading the fuel lines and separator but still having low fuel pressure, Rudy installed a CV Products Spin-MP2517 fuel pump. With the new fuel pump problem solved with a WOT fuel pressure at a steady 7.5 PSI. The Dryden engine has performed flawlessly for 2 seasons.

The Carter M61045 fuel pump was returned to the engine builder who then returned it to Carter to be tested. The following quotes are from the letter sent to me by the engine builder with their punctuation:
“ Observations and Analysis: The submitted mechanical fuel pump appears to be in good operating condition. The pump took 13 strokes to prime the supply line and at 60 RPM’s it delivered an average of 27 cc’s per stroke. The pump produced a flow of 60.1 gallons per hour at 1800 RPM’s and restricted to 2 psi. The static (dead head) pressure was 6.21 psi. All of these parameters are within manufacturing specifications for the submitted pump. The pump operated smooth and without an abnormal noise.
It has been determined that the fuel pump installed in your engine was not faulty. It has also been determined that the pump used in your engine was the proper pump for your application. Clearly the pump is not the cause of the engine failure, which further indicates that the fuel lines were not adequate.”

I do not understand how fuel pressure and volume affect the fuel pump so the fuel pump delivers the correct fuel requirement for the engine. Even not understanding that, after the rebuild and steps taken to diagnose the fuel problem, I am of the opinion that the Carter fuel pump was the cause of the detonation and subsequent engine failure.

What is your opinion? Was the engine dealer installed Carter M61045 inadequate or cause my engine failure?

Thanks again for your responses.
Steve

GTOFFSHORE

I think the fuel pump was doing what it could. The demands of your 540 at those rpm were taxing it and you didn't have enough volume of fuel. A 502 mpi turning 4600 rpm is a lot less wanting than a 5600+rpm 540. It might work on paper but obviously didn't in real life. According to your Dyno it looked a little week. I wonder why it was not upgraded then. 5 psi isnt bad but 6 would be better IMO. But in the end it was probably volume that killed it.

Brad Zastrow

Fuel flow killed it not pressure. Sounds like you had restrictive lines and filters. Even the tank pickups could have been too small. Too many times bad rigging (stock rigging) will kill high perf engines and the builder gets blamed. Small fuel lines, restrictive fuel pick-ups, 90 degree brass fittings, small water seperators all are engine killers.

VetteSteve

Restricted Fuel flow through the fuel lines and filter separator were eliminated as being the cause of the low fuel pressure because after they were upgraded the low reading were still present.

Rudy was not happy with the numbers so first he upgraded the original 502’s Mercruiser fuel lines and water/fuel separator. Then another test run provided the same fluctuating fuel pressure of 3.75 to 4 PSI.

mike tkach

iTrader: (3)

in your origional post,you said fuel lines&filter head were replaced with larger parts,and the problem still existed,then the pump was upgraded and the problem was gone,it seems to me the volume of the first pump was not adiquit for the demands of the engine,just my poinion.

kvogt

The engine dealer installed parts: fuel pump was a Carter M61045, Carburetor is a Holly 1150, Compression Ratio: 9.490: 1, ignition timing at final advance is 34.0 degrees BTDC @ 4500 rpm. The dyno sheet provided by the builder states; peak torque at 4900 rpm – 611.4 HP - 654 torque – fuel pressure 4.967 Psi; peak HP at 5900 rpm – 670.3 HP – 595.5 torque – fuel pressure 5.009 Psi.



5 psi is the minimum you want to see. I would think the dyno fuel system is better (less restriction) than your boat so I'm wondering why that wasn't addressed on the dyno. But: did the engine builder just build up an existing motor, who did the install and shakedown run, was it fresh build from the ground up???

kvogt

I was reading this again and this part does not make sense to me.

In 2009 I had a 540 C.I. normally aspirated marine engine built by an engine dealer. After 19 hours the engine failed. In June of 2010 while running at WOT, 5600 rpm, cylinder #6 incurred a ½” hole in the dart aluminum cylinder head caused by detonation. Because of the hole went into the water jacket, water flow was lost and the engine over heated and the heat tabs melted. The engine required a rebuild.

Detonation caused a hole in the head? Then waterflow lost because of the hole in the head?

VetteSteve

The engine was ordered and built by a non local engine dealer. The complete engine was shipped to and installed by my local marine mechanic who I have used for years. After the engine failure the engine builder sent me to Rudy who had a working relationship with the engine builder. Rudy is local to me.

The 1/2 inch hole in the cylinder head was into the water passages of the cylinder head. Water flow was now being sucked into and pumped out of the cylinder. So now water was not circulating though the block cooling it. Thus the engine over heated.

kvogt

My take on this is. The installer should check for things like water temp, water pressure/flow, oil temp, oil pressure and fuel pressure this includes idle as well as wide open throttle. These are the variables that change when going from a dyno to someones boat. Jetting can also change but it sticky messing with an engine builders jetting.

I don't understand the hole in the head. Usually if the motor has sufficient cooling and is detonating the piston will fail before the head. The only times I've seen a hole in the head is when something knocked a hole in the head like a valve.

As far as overheating the motor, the sea pump still would be suppling a large volume of cooling water to the engine and the water being "pumped" by the piston would probably aireate it some but that water would be exiting the motor through the exhaust port and the cooling system. When this happened there would be a big decrease in performance, the engine tone would change and the motor probably wouldn't idle in gear any more. To me I don't understand how the engine heat indicators showed hot from any of this.

Johnb

The part number M61045 provided by the builder is not listed in Summit, Jegs or the Carter web site. The closest part number is M6104. This is a stock replacement pump for a 454. The builder should clarify the pump model and application. The 6100 series is not listed anywhere in the "high performance" pumps offered by Carter. This does not factually state that part number M6104 does not exist- it is at the very least hard to find.



The response from the builder is off of their key board- post the original findings on the original document from the testing house (Carter).



The actual test:

Diaphram pumps are very efficient - up to 97%. However the check valve assemblies are not. As rpm/flow increases inefficiencies will increase due to the valve limitations. I find it interesting that the test was at 60rpm - which is a industrial diaphram test. 60.1 gallons @ 1800 rpm at 2psi ... Why wasn't the pump ran at running rpm and 7psi? I think we all understand that flow is inversely proportional to pressure. So a nearly 60.1 gallon free flow at 2psi at 5400 (3x test) would theoretically flow 180 gallons at 100% efficiency. However that is only approximately 51 gallons at 5400rpm at 7psi. That will support 600hp - if the pump is 100% efficient and the check valves are 100% efficient - which is not real world.

At 600hp the pump is still undersized. Pumps as a rule of thumb should flow at least 130% of requirements.



Rudy measured 4 psi (which has witnesses) - assuming the pump is running as tested/witnessed it was only delivering 29gph at WOT.

Honestly (emotions here) I would expect more out of a $202 pump (price to customer).



1) The system in the boat measured 4psi immediately after the melt down.

2) The system measured 4psi after the line and filter change.

3) The system measured 7psi after the line, filter and PUMP change.



So either the pump is an issue or Rudy is not telling the truth. The pump and original test docs are not available so draw your own conclusion at this time.



Unfortunately the builder has the pump which is the only evidence.



While I agree in the owner rigging resposibility:

The builder is the expert- items of engine rigging, timing, fuel etc.. should be described in the contract/agreement between the two parties. As a business owner - final installation - should not be left in the hands of the customer 100% unless you want issues... Especially when it is as simple as this.







In the end where is the original pump? What is that part number?



What is the inlet size of the pump? It is not a high performance unit with -10 or -12 in it. If it is a stock replacement pump as the part number seems to indicate the line is 3/8 or 7/16- I am not aware of any 1970 Chevy Corvettes with 1/2 fuel lines... What did the builder feed this pump with? A dyno- the dyno's I have seen have large electrics tied to them and fuel pressure is set per application. What does the dyno sheet show? Fuel pressure?



At this moment I would say the builder let the customer down and has not proven their point.