89 5.7 Cobra running issies

[Cjpainten]

Just picked up a new boat and had a few questions on where I should start looking

The boat requires starter fluid to get going, and a few attempts at cranking, when it finally gets it finally gets going it idles and revs good but under a heavy load it dies.

It has a new carb (Sierra) but the previous owner thought this may have been the culprit since it was running great before he swapped it out (original quadrajet had bad seals)

I have a fuel pump laying around I was going to try to throw on and see if this fixes it.

Also have an Edelbrock 1409 that I may throw on in case the pump doesn't do it.

Anyone have any other ideas or suggestions?

 

[Lou C]

If he still has the original Quadrajet you might want to try rebuilding that first.
OMC switched to the Holley 4bbl carb in '90, that might be an easier conversion. The issue with putting an Edelbrock on an OMC application is that the Edel is wider on the side next to the shift bracket/trim relays, and the fuel line has to snake in there too. You would probably have to remove the trim relay and re-locate it for the carb to fit. I did that when I changed my Q-Jet to the Holley 4160....

http://www.crowleymarine.com/johnson-evinrude/parts/55845.cfm?mdl=LVV7FY
Since this does not use an adapter on the Q-Jet style manifold, it is likely a Holley 4175 spread bore which is still available from Holley brand new.

 

[Cjpainten]

No he doesn't have it anymore..

I was under the impression the 1409 was a direct swap

 

[Cjpainten]

https://forums.iboats.com/forum/eng...989-5-7-quadrajet-to-edelbrock-1409-swap-help

 

[bruceb58]

With the engine not running, have someone operate the throttle while seeing if the accelerator pump is squirting fuel down the throat of your carb. If it isn't, that is your issue. Also, not sure how you attempt to start your engine, but you always need to pump the throttle a couple of times to start when cold.

As far as dying under high load, that could be a carb issue(float level) or a fuel pump delivery issue.

Bad idea using starter fluid. It is very volatile so if a cylinder's fuel ignites on the the piston's upward travel, you could bend a rod. If you have to use something, just pour a couple ounces of fuel down the carb throat. Of course you want to fix your issue instead of relying on that.

 

[Lou C]

I just swapped a 4160 for a Q-Jet which is what OMC used from '90 on and trust me nothing is a direct swap. For example, in '90 OMC changed the relay set up for the trim system, so the issue of no clearance on the side of the engine where the shift linkage mount is became less of a problem. But you have an '89 with the old style big relays. Also, there is a different fuel line (Sierra makes a flex line you can use), the Edel is a square bore carb, you have a spread bore manifold and will have to use an adapter plate. Then, sometimes the throttle bracket on the intake manifold needs to be changed, because if it puts the cable at too much of an angle up or down the cable can bind. So, to do my conversion I had to:
find the OMC adapter, the aftermarket ones don't fit as well
get the OMC steel fuel line
wire up a relay for the auto choke (electric)
fab up a throttle cable bracket because the OE one for the Q-Jet was too high putting the cable in a bind, and the one they used with the Holley is NLA.
And this is for a carb that WAS used on this engine!
The Holley is at least calibrated for the OMC/Volvo 4.3 V6.

The Edelbrock is well thought of, but keep in mind the points I made. You will be fiddling with it for a while to get it dialed in. It is not really plug and play.

Keep in mind that link you have up above is for a Mercruiser engine. The Merc shift linkage is not in the middle of the way because it is mounted to the exhaust elbow higher up, not low down right over the intake and valve cover like on the OMC. On the V-8 you have a bit more room because the intake is obviously longer than on the V6. I can tell you for sure the Edelbrock will not fit an OMC Cobra rigged V6, unless you relocate the whole shift linkage bracket higher up. I could have done that but went with the Holley instead. Both OMC and Volvo used Holley carbs till the end of their using carbs when they went to throttle body FI. Also the set up on a Merc engine is easier because Merc switched to the Weber 4bbl after they stopped using the Q-Jet years back and the Edelbrock is nearly identical to the Weber. So it fits easily on a Merc rigged engine.

PS what Sierra carb do you have? Is it a rebuilt Q-Jet? Or the new copy of a Q-Jet they were supposedly selling?
I saw on some boat part webpages that they were selling a new copy of a Q-Jet and I asked a few marine mechanics about using it and they advised me not to.

 

[Cjpainten]

I believe it's the new one but I have to check when I get home tonight

 

[Lou C]

http://www.seastarsolutions.com/pro...rts/fuel-systems/carburetors/new-carburetors/

this one?

 

[Cjpainten]

Quick update...

Had my fiancee pump the throttle as I was watching and yes it does squirt 2 nice streams so that is not the issue. It also started immediately after with no hesitation.

I let it idle a few minutes and began revving it up a bit. It didn't stall or sputter.

I then attempted to go from idle to WOT a few times and got it to stall that way. She started back up with applying about 1/2 throttle

Upon further investigation I am seeing tiny beads of what I assume are water around the bowls inside the carb.

This boat has a fuel/water separator so am I correct to assume it's filled beyond capacity? Can I just unscrew it and dump the contents out then reuse?

Water in fuel seems to be my culprit

 

[Cjpainten]

And yes that's the one!!

 

[Bondo]

This boat has a fuel/water separator so am I correct to assume it's filled beyond capacity? Can I just unscrew it and dump the contents out then reuse?

Ayuh,..... Only if ya wanta pump more crap into the carb,.....

Ya gotta pull the filter, 'n examine it's contents, for anything but clean fresh gasoline,.......
What ya find, tells ya which way to go to fix the issue,....

A clear container is the key,..... I use freezer baggies,.....

Crack the filter loose, slip the baggie 'round it, spin it off, seal the baggie, 'n tip it over,.....

Always,.... Always replace with a New filter,.....

 

[Cjpainten]

Ok so now I am beginning to think it's ignition related. Fuel delivery all seems ok. It does miss and backfire a little around 2500rpm

 

[Cjpainten]

Just slipped off the filter and dumped it out. Fuel Looks decent but there is a lot of black crap in it. just to make sure I also siphoned a good 5" off the bottom of the tank

 

[Cjpainten]

[No message]

 

[Cjpainten]

Talked to the previous owner and apparently the boat ran fine until he switched the carb and it all went downhill from there. Should I try the Edelbrock or am I better off getting a Holley?

 

[PITBoat]

Bad idea using starter fluid. It is very volatile so if a cylinder's fuel ignites on the the piston's upward travel, you could bend a rod. If you have to use something, just pour a couple ounces of fuel down the carb throat. Of course you want to fix your issue instead of relying on that.

What would ignite it if it's timed correctly? I use it on my old pickup if it sits for more than a week, to save the starter.

 

[PITBoat]

I tried the new carburetor route once and it didn't work out. I dipped and rebuilt my quadrajet and had much better results.

 

[Lou C]

Well judging what the gas looked like my first thought would be to get the gas tank cleaned out. While fuel filters do help, the amount of sediment there could cause a problem with clogging filters and also water built up. I would carefully remove the sending unit for the gas tank (pick up a new gasket) and shine a bright LED flashlight down to the bottom of the tank. If you see debris and water down there, at least try to pump it out till you see clean gas.

Back to the carb, if this is the new Sierra Quadrajet you might need to go through it to make sure the float is set right and the passages are all clean. The Q-Jet is an excellent carb when clean and set up right, but it is more complex to take apart and clean and re-assemble. Both the Holley and Edelbrock are simpler designs, easier for the backyard mechanic. I'd do this before buying any other carb.

If you already have the Edelbrock, then nothing to lose by taking off the Q-Jet to clean it, and trying the Edelbrock on your manifold to see if it will clear the trim relays. If you use a banjo style fuel line and re-locate the front relay to the rear of the shift bracket (this is what I did to make the Holley fit), you may be able to use it. However, then you need to work through the throttle cable set up and of course the jets and metering rods may need to be changed to suit your engine. I have read that due to the dual bolt pattern of the Edelbrock, sometimes the gasket will cover the wider secondary bore openings of the spread bore manifold but sometimes it doesn't. This would cause an obvious vaccum leak and there is apparently a thin steel plate you can use to completely cover the wider secondary bores on that intake. Other option but more $$$ is to use an Edelbrock marine intake if one fits your applications. The Edelbrock carb should work perfect with that intake.

In this pic this relay was moved from where it is, to the rear of the shift linkage bracket. I just had to extend the wires a bit to make it work, that gave enough room for the secondary diaphragm of the Holley to fit.

 

[Cjpainten]

I would rather repair what I have than open up my new carb. Where should I start looking to see whether or not the float is set correctly?

 

[Cjpainten]

It real runs good until the secondarys begin to open up