5.7 Crusader Engine Problems

[Porch Swing]

HI, New to the forum and boat the Ohio River and looking for some possible assistance with my crusader engines. I have a 1992, 43', Bluewater Coastal Cruiser with 5.7 Crusader engines. It has a AC delco HEI distributor and ignition system (electronic)

Last year in July my Starboard engine would not allow me to go above 2500 rpms or it would die until I pulled back on throttle, August it would not go over 1800 and now today, it does it at 1500 rpms. It is getting plenty of fuel (filled a 12 oz bottle in a few turns of motor). Engine starts right back up after it stalls, just won't take fuel over those RPMs

I have changed the coil, dist cap, rotor, fuel filter and plugs. Spark plug wires are 4 years old. It does not have a ballast resistor or wire or a pre-fuel filter strainer. The only thing I have not changed is the module in the distributor that two wires plug into through the bottom side of distributor cap.

Not sure where to go from here and wondering if anyone has any suggestions.

Thanks in advance.
Rick

[a64pilot]

I still think it's fuel flow related, or sure sounds like it. Try this see what happens, if you nail it from an idle, will it initially rev up, but then die a few seconds after you nail it? In gear, not in neutral although if it will rev high in neutral that ought to rule out ignition.
Ignition failures usually show up as miss fires at higher RPM, it'll turn up, but start "busting up", meaning bad misfiring, not usually die out, but re-start, that sure sounds like fuel flow.

Do you have the little filters in the carb float bowl too, My old 454's did. Have to take the fitting out that the fuel line attaches to.

[Porch Swing]

Has a new filter in the carb where the line attaches. Forgot to mention Carbs were just rebuilt.

I will pay more attention the next time I get it out of harbor. It will run at high RPMs in gear for a bit, then die off and it gets worse as we go. Rev's up in neutral with no problem.

One other thing I tried was to blow air with my mouth through air through the supply line from the tank thinking it might be clogged. I could not blow though it, but not sure if it doesn't have some sort of one way check valve that keeps fuel from draining back into the tank. thought maybe might have a (sock) strainer on the end of the pickup tube in the tank.

Will let you know what I find. When you say install a cheap fuel pressure gauge in the line, do you a permanent one or just to check with a gage?

[Cheechako]

Doesn't sound like ignition to me, unless you've got the timing out of whack or something. Just the one engine right? so not a heavily loaded bottom condition.... Did this start after the carb rebuild?

[a64pilot]

Pressure gauge would confirm fuel delivery, pressure woudl go to zero or close to it just before it died.
Just a temporary one, I have never seen a check valve in a fuel line, I believe the mechanical fuel pump functions in that capacity, and of course you have the fuel in the carburetor you could run on until the line re-primed.
It could also be an improperly set float level, or a sticking float or even needle.
Carbs are a PIA, but easy to diagnose and fix.
If fuel pressure doesn't drop off, I'd suspect float, or heck just pull the carb and check.
Four barrel, right? Maybe the secondaries are dry and it runs til the secondaries open up, or fuel restriction to secondaries?
Unlikely you open the secondaries unless in gear, vacuum secondaries I'd suppose

[a64pilot]

Originally Posted by Porch Swing

I will pay more attention the next time I get it out of harbor. It will run at high RPMs in gear for a bit, then die off and it gets worse as we go. Rev's up in neutral with no problem.

[/FONT]

That sounds exactly like classical clogged fuel line, like you say, I'd look for a sock on the end of the fuel line

[Porch Swing]

Thanks. No, it was doing it before carbs were rebuilt. I am going to disconnect fuel supply line and use another source of fuel and line and rule out pick up tube in tank.

[a64pilot]

Your going to tie in just before the mechanical pump I suppose?
Since your going to all that trouble, get a cheap fuel pressure gauge, only needs to read about 5 PSI or so.

Do you have access to an outboard engine fuel tank?

[Porch Swing]

Yes and yes. I will let you know what happens.

[Lepke]

Long ago I had a similar problem with a sports car. It turned out some kids put sawdust in my tank. The sawdust collected at the incoming edge of an inline transparent fuel filter within the black fuel hose. So I would look at the filter and see it was clean. Eventually I ran a temporary fuel line and everthing worked fine. Then I forced compressed air thru the existing line toward the tank and discovered the sawdust.

[Cheechako]

I was going to mention maybe a clogged pickup tube or something in the tank, but only does it on one engine right?.. do the engines have separate tanks?

[Porch Swing]

thanks. I have one large tank it appears and all the pick up tubes are for both engines and Generator are all in the same location. I am going to switch the fuel lines at tank and see if I have a plugged pick up. The Port engine is working fine.

[a64pilot]

Often the dip tube is screwed into a bung welded to the tank, if it is, maybe just disconnect the line and unscrew the tube? then disconnect from the pump and blow though to make sure nothing is in the tube.
When I bought my boat, I didn't get more than two or three hours away before RPM began to drop, it took a little while to figure it out as in my case "stuff" had been sucked up into the tube and actually didn't plug up until it hit the elbow at the top of the tube.
At first I though it was a lift pump, but finally figured it out when I couldn't blow through the line.
Diesel, but similar principle, just Diesel grows stuff in it under the right conditions.

[Porch Swing]

Thanks. The pick up tubes are welded in place on this one. I know I couldn't blow through the supply line into the tank when I tried. There might be a clog. I don't remember any of my old boats having a sock in the tank.

Just thinking out loud here. Wonder if the fuel lines in this boat were exposed to years of ethanol fuel and the interior of fuel line closing up while in operation.

[a64pilot]

If it is, is there an elbow?
Can you get a straight shot down the tube? Maybe a brass rifle cleaning brush would clean it out if it is clogged up?

Your a gas boat, meaning of course you have to be especially careful spark and static electricity wise