7.4L TBI fuel pressure problems

[RGrew176]

Fortunately non ethanol gasoline is still widely available here in my area. Hope it stays that way.

[Midnightsun]

In Canada it is difficult to know what you are getting speaking strictly road pumps that is. Most pumps indicate "may contain up to 10% ethanol" Petro Canada on the other hand is labeled the same but only for regular, mid grade is labelled as up to 5% ethanol and super labeled as containing no ethanol.

As for marinas, most have signs that say ethanol free on both Canadian and US sides, now whether one believes what is written can be challenging to say the least. Oddly enough, most gas at the marinas are high octane (super) yet none of our gas engine boats require this.

[mjk1040]

FYI, I was in the wholesale fuel business for awhile and can tell you that the wholesale cost then between regular and super gasoline was only a few pennies more, yet retailers try to get many more pennies at the pump. I understand why the same gasoline at the pump for vehicles is dollars more at the marina do to liability insurance cost related to potential fuel spills and water contamination. But I can not understand why a marina would sell the low octane gasoline when the higher ethanol free gasoline does not cost that much more at wholesale and would only make every boaters life so much easier! Tom, it may be called the office of consumer affairs in your area? I can't believe there is not some office that doesn't regulate retail sales in your area. The pump seals are to assure the pumps are dispensing the amount of fuel that the pump is saying you are getting. Here in NY these same offices are also required by EPA to randomly test octane levels in all fuels sold, not only gasoline but diesel too!

[Midnightsun]

Here in Canada we get raped with high octane. Most of the time it is at a 20% premium over regular. Guess they needed to justify the new meaning for the word "premium". Just checked gas buddy and my local gas station is $1.06 for regular and $1.25 for premium.

Problem is the trend is towards smaller turbo charged engines that require mostly premium fuel, hard to justify the extra MPG when the fuel costs 20% more. A rather important item not to be overlooked as it is equivalent in your wallet to a car that gets 20% better milage.

IMHO EPA ratings should show when a car REQUIRES premium as a monetary figure translated to MPG so everyone can understand the impact and get a better overall picture. We all look at MPG as cost savings but those numbers are very skewed when it comes to the type of gasoline required.

City 25mpg, Premium Fuel Cost Adjustment Equivalent 20MPG
Highway 35mpg, Premium Fuel Cost Adjustment Equivalent 28MPG

[tomschauer]

Mike, the gas stations have their pumps checked and sealed bi annually by the bureau of weights and measures. I just don't think the marinas have the requirement, but I may be mistaken.

[RaRa]

My Mercruisers have issues like this. Thing is, runs up to full RPM sitting at dock. This is the port engine. Starboard is fine. I guess I have some items to check instead of sitting in engine space wondering why? Or maybe it is time to have a qualified mechanic take a look. As shipmates say, if it is going to happen, it will happen out there.

[mjk1040]

Tom, I got to think if they are sealing vehicle pumps that marine pumps would not be exempt since it's a dispensing device and should be sealed that you are getting what the pumps says your getting. RaRa, have you done the simple tune up on the lagging engine ?Fuel filters, plugs, cap & rotor? Maybe run some good injector cleaner thru your fuel system. I think there is an inline injector cleaners that could be applied as in a over the road vehicle!

[bud37]

Source of the post My Mercruisers have issues like this. Thing is, runs up to full RPM sitting at dock. This is the port engine. Starboard is fine. I guess I have some items to check instead of sitting in engine space wondering why? Or maybe it is time to have a qualified mechanic take a look. As shipmates say, if it is going to happen, it will happen out there.

It takes very , very little fuel to rev an engine to full rpm when there is no load ( neutral ), the practice of revving an engine to full rpm at the dock is not a good idea, actually doesn't show anything and you can damage things doing that.

Like Mike says maybe a tune up is in order, carb rebuild, have someone look at the distributor etc.....

[km1125]

Source of the post My Mercruisers have issues like this. Thing is, runs up to full RPM sitting at dock. This is the port engine. Starboard is fine. I guess I have some items to check instead of sitting in engine space wondering why? Or maybe it is time to have a qualified mechanic take a look. As shipmates say, if it is going to happen, it will happen out there.

Step #1 should be to change ALL the fuel filters if it's either been a while or you don't know when they were changed. Make sure you get them ALL. Sometimes there's two or three on each engine and folks just change the "main" one. Next would be to check or replace the siphon valves. Then, if you're still having issues I'd start looking at fuel pressure (if injected) and spark advance. The fuel filters are maintenance items and it never hurts to have good ones in there unless you do some damage when you're replacing them.

[Cooler]

I do not believe the 90 Montego's were fuel injected. Sounds like complete tune-up as mentioned above or carb rebuild. Do you burn non-ethanol gas only? If you are running & storing with ethanol, carb rebuild, filters & tune-up. er