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Fuel Pump not pumping: Gen IV Crusader 454

M

major_tom

Regular Contributor
I'm helping a friend trouble shoot a fuel delivery problem on his starboard Gen IV Crusader 454 with mechanical fuel pumps.* His Port motor has no issues and is connected to the same fuel tank as the starboard motor thats getting no gas.* We swapped fuel lines at the fuel tank pickup (there's one for each motor) thinking maybe the anit-siphon valve was misbehaving or perhaps the pickup was clogged, but the*Port motor runs fine on the starboard pickup and the starboard motor still doesn't run with the carb completely dry.* If we pour fuel*in*the starboard carb it will fire right up.

We disconnected the fuel line at the starboard carb and cranked the engine--no fuel.* We were able to blow fuel back from the connection at the tank to the input of*the starboard fuel pump so the lines are not clogged.* Also*both the*bulkhead mounted fuel*filters and the engine mounted canister filters are brand new.

We bought another pump even though the mechanical ones rarely fail.* This was installed while I was away but it doesn't pump either, and the one we took out seems perfectly fine.* One of our dockmates is pretty sure the push rod to the pump that was replaced is bent, which could very well be the problem.* The other possibility is a wiped cam lobe*at the pump push rod.* If that's the case maybe an electric pump is in our future...

Any advice on further trobule shooting, push rod replacement, or installing an electric pump would be most appreciated.

Best wishes,

Tom
 
Hi Tom - welcome back to the land of spark ignition!

This is based on the starboard engine starting up and then stopping when the fuel in the carb is depleted....

I'd be hard pressed to believe the pump's push rod is bent...fastest test would be to hook up a vacuum gauge on the suction side of the fuel pump (see if the spin on filter head has a pipe plug that can be removed. fill the carb's bowl and start the engine...the vacuum gauge should indicate a few inches of vacuum if the pump is working...if it is zero, there's a leak or the lob driving the push rod could be wiped. the later will require removal of the pump and a physical inspection. I'd be inclined to spin the engine over manually and take a measurement on the push rod every 1/3 to 1/2 turn of the crank, for two revolutions. The total rod movement is just over 0.3".
 
Thanks Mako.

Yes, its based on a no start condition (dry carb bowl). If you pour some gas in it will run for a while then stall. I wasn't sure if the push rod would stay up against the cam lob so that its deflection could be measured. If so that's worth a try since it will be diagnotic for a worn cam lob. Taking the push rod completely out will allow visual inspection if there is clearence to do so.

So you are thinking worn cam lob or vacuum leak, right?

I replaced a cam once and its a big job although not a technically diffiucult one. Any reason a block off plate and an electric pump can'te be used?
 
the pump lever has a return spring; that is what keeps the push rod against the cam lobe. when you pull the pump, the rod will slide down in its bore.
Unless you have a borescope, removing the pushrod will NOT let you see the cam. going on memory, i don't think the bore is more than 0.5" and the cam is about 6" from the mounting flange....

I'd say you have a fuel delivery problem. If it turns out to be a worn cam, the electric pump would be the fastest solution. If you go down that route, be sure to add the oil pressure safety switch.
 
Borrow a portable outboard tank with the fuel line & priming bulb.Take the fire extinguisher out of the bracket and keep it handy. Remove your fuel line at the filter inlet and connect the test tank line in its place, tighten the hose clamp. Squeeze the priming bulb until its hard. Check for leaks as you do this.We have now pressurized the section the fuel system from the separator to the pump, any leaks should show up. If no leaks, start up and see what happens. If it runs for a bit and dies see if you can keep it running by squeezing the priming bulb. Than you will know for sure its the pump. If it runs fine try the same test at the tank to eliminate that section. If you cant find anything and it runs normally after you put everything back you may have had some kind of air lock that you cleared.
 
Good suggestion. We tried a portable tank but did not use the primer bulb. No luck though, the pump would not take fuel from the portable tank. Seems like if it was pulling any vaccum at all it would have run on the portable tank. There is another thread on this topic started by Douglas57. Right now the fuel pump push rod is jammed in the bore and not moving when the engine is cranked. That's got to come out one way or another. We tried some pliers with circular jaws but its stuck pretty good. Might have to remove the intake manifold to get to the lifter valley, although I'm not sure it can be tapped out from above once the intake is off.
 
Macomark,

What does it mean for the cam lob to be "wiped". I am having a similar problem to this thread. I have a 1989 454 Crusader engine that had been running fine and then after restarting after a few hours rest, there was a "pop" sound (maybe a backfire) and the engine died. I did some troubleshooting and with the fuel line disconnected at the carb and cranking the engine there is no fuel, or just a few drips, coming out. The anti-siphon valve and f/w filter are clean and the line from the filter (spin-on type mounted on front of engine) to the tank is clean and clear or any obstruction. So I plan on replacing the pump, although I have not yet removed it. There is no gas in the sight tube which would indicate a leak in the main diaphram so I am at a loss as to how a pump would just stop working like this. I am not trying to hijack this thread but maybe add some info to it that would help me and others.

Thanks,
Erich
 
A wiped lobe means the high point of the eccentric has been removed, usually through physical means; ie instead of a lobe, you have a circle (or close enough).

These pumps have more than one failure mechanism...if the cam is intact, it could just be the diaphragm has stretched enough to stop pumping. Another possibility is for crud to have landed in one of the check valves which will also inhibit the pumping action.
 
Hi Erich:

We installed an electric fuel pump kit because the fuel pump push rod got jammed inside the block trying to trouble shoot the "no fuel" condition. After the install of the electric pump the engine fired instantly and worked great for a few days.

However on the way back from our latest trip the engine stalled just after the throttles were choped from 3/4 to idle speed upon entering a no wake zone. The boat had been running great until then. The owner had to dock on one engine. A few minutes later the engine fired right up, leading us to believe it might have flooded when the throttles were chopped. The carb is pretty dirty, acclerator pump is stuck, etc. and so it will be removed and serviced this week.

There is still some bad behavior going on. Quite possibly a vacuum leak between the pump and fuel tank. Other possiblities are a faulty pump or bad electrical connections/ground to pump. We haven't had time to trouble shoot the latest issues. The following day the engine would not start again. We are back to square one and will need to trace back through all the fuel and electrical connections once more. We plan on doing so this week.

On a slightly humorous note the boat was invaded by a squirrel while all this was going on. When it rains it pours. Squirrels are not your friends and our attention turned from fuel issues to squirrel removal. I'm happy to report that on Monday the squirrel problem was 100% resolved.

Best wishes,

Tom
 
makomark, thanks for the explanation.

Tom, thanks for that update. I hope you are able to get all the remaining bugs out.
 
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