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Loss of power

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Dave Karrer

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"My 88 Shamrock with 302 Ford

"My 88 Shamrock with 302 Ford has lost power and will not get up on plane. It has 1300 hours on it. I have checked all systems and filters and they seem to be working fine.
Could the exhaust pipes under the floor be rusted enough to choke off the power? Where can I get them? Do I need them? Has anyone had a similar problem? I am running out of things to check.
146498.jpg
"Over Kill"
 
I have an 87 Shamrock qith abo

I have an 87 Shamrock qith about the same hours. I just replaced the heads for an unrelated problem. I did replace the exhaust with 3" fiberglass pipes. You have to replace the through huls too since they are 2" or 2 1/2". This has worked very good for about 5 years now.

I once had a problem that turned out to be the fuel line at the filter. It was loose and drawing air into the fuel an starving the engine.

The first things to check are the spark plug wires. One way is to pull them from the distributer and set them loose on the distributer cap. Then pull one at a time to see if the engine slows down . Do this all at an idle. If there is a problem replace the spark plug wire. and recheck. Next check the plugs to see how they look. There are some pictures in most repair manuals that will show how a normal plug should look and what they look like if there is a problem. Plugs are hard to pull because of the exhaust manifold. I would chenc the compression at that time too. It should be around 150lbs or more.

Check the throtle linkage with out the engine running to be sure it can pull the carberator wide open when the throtle is pushed full forward.
You can also remove one of the bottom bolts on the front of the float and drain the carb incase there is some water in the float bowel. Do this only when the engine is cold and have a rag to catch the fuel that will come out. It is not much only a couple of ounces but would be very dangerous with a hot or warm engine. Take the rag off the boat and let it dry then thoow it away.

Hope this helps.
 
"Thanks for the suggestions.

"Thanks for the suggestions.
Here is what I have done so far. Changed plugs, wires, cap, rotor, coil, and fuel/water seperator. They were all OK but old. I have electronic ignition so no points or condenser gap was OK from ring to unit. Checked spark and timing. Also advance springs in distributor were OK.
Need to do compression test but when I pulled spark plug wires one at a time in idle, all cylinders seemed to be equal

Will check fuel lines. Maybe some air getting in and all fuel going into the carb is being used by the primaries.

Engine seems to start and run perfectly normal at idle and up to half throttle. I have stroked the throttle plates and they open fully. I have noticed the whooshing sound from the secondaries is muted but there seems to be fuel going in just no RPMs after about 2400."
 
"Dave,

From across the str


"Dave,

From across the street it sounds like a fuel supply problem. I wouldn't go much further without doing a compression test, but I would check fuel flow as well. Filters may be fine, but a stuck anti-siphon valve or a delaminated fuel line will cause a restriction too. Double check to see that you have cleaned or replaced <u>every</u> filter, including the one in the carb."
 
Hi all...
I recently acquire


Hi all...
I recently acquired a 20' Shamrock... maybe 1985?(4)? It only has an engine& trim/ bilge pumps & exhaust (engine done by someone else)... still needs ALL electrical/ steering etc. The engine is a Ford 351... (Cleveland I believe) and an inboard. I will most likely be using hydraulic steering.

Im here because the previous owner intended to use a Grady White wiring Schematic for a 1984 / 88' or so. I was able to find one & download. He says they have the best wiring plans or layouts etc. Ive tried to find an already prepared harness instead of wiring every single piece or item separately... but havn't been able too. I'm sure I'm also adding much more than this 1984 schematic has?
After reading some of this stuff I'm wondering if anyone would have a suggestion on what to do? I am absolutely clueless to any of it!! Talk about LOST!?
I've hardly ever even been on a boat & now I'm building one!

I was helping a friend who this boat was his life project... totally re-did fiberglass top to bottom down to new wood & stringers... beautifully!! Put gorgeous handrails & teak trim along the top edge. A marina was going to reposess it for money he owed for engine rebuild/install etc... so I paid the bill. He's fallen on VERY hard times & felt he had no choice but to sell it (although I didn't ask for money back anytime soon at all). It broke my heart... this was all he had... so I decided to buy it myself instead of a stranger... Ta-Da!... here I am!
HHHHEEEELLLPPPP.......... Pleeeease?
Thanks for the listen & patience with my total inexperience!
Cathy

ps... what was i thinking?!
 
cathy is the motor a pcm or in

cathy is the motor a pcm or indamar the engine should have a wire harness you can get schematics on either engine an wire it to the gauges
 
Hi Jim... Unfortunaely I don&

Hi Jim... Unfortunaely I don't know what either of those are... pcm/indamar? If you could explain in laymans(or car?) terms... I might know. The engine isn't connected to anything yet since I'm in the process of getting gauges now... along w/all else. Just laid in there for the moment... close enough to easily align later. This is how I got it... basically a finished shell (beautifully finished!) So everything is up for grabs at this point. The center console doesn't have a hole in it & there is not a wire or light or mechanics anywhere on the boat(bilge just done)
Are you suggesting I find a schematic for this engine instead of the Grady specs? I'm not sure what you mean... sorry & thanks
 
I have a 20' Shamrock 1987

I have a 20' Shamrock 1987 and I bought the manual for it. It should have a PMC Engine. Both Indmar and PMC are marine engine conversions of a Ford 302.
I cna send you the wiring diagram if it would help. The wiring harness uses plugs like a trailor plug but more pins. There is three. One for the enging and one for the back lights one for the front lights. I don't know where you can find replacements but they are handy if you have to disconnect anything. Mine is a center console so I may have to remove the console during an engine replacement.
I may be able to scan the pages and send them as a pdf if you send me an email address.
 
hi cathy e basic power has har

hi cathy e basic power has harness or try discount inboard marine they are helpfull you can go on fish the classic its a shamrock boat owners web site check some post there its help full as well theres always some one there doing something to there boat
 
"Thanks for all the help with

"Thanks for all the help with this stuff!! I may ask for the wiring diagram from you... that was for the Shamrock right? Don't know why he was going to use the Grady one but I do have that. I did try a few suggested sites which are helpful. I also contacted Shamrock & Grady places. Mines a center console as well and its not yet bolted in place... which should make everything easier for now.
I'm looking at hydraulic steering helms & cylinders too. This is just way beyond how hard I thought it would be!
I was told engine was the 351 but whether indamar or pmc... I still dont know.
I now have to figure out if its a 'Planing hull' or 'displacement hull' to get the right hydraulic steering system. Something about the difference being one's hull speed excedes 18 knots & other was under. Anyone know how many MPH a knot is or if my boat goes over or under that?... so crazy! There's a hyd. cylinder 4 sale but it came from a 39' sunfish sail? Says... stroke:7'', produce 600kg at 50kg/cm. Yes... like I know what that is? TE HE HE!!
I'm just going to keep asking questions & researching everything & eventually it WILL get done... BUT WILL IT FLOAT?!?!"
 
your boat should go faster tha

your boat should go faster than 18 knots a knot is 1.2mph you should cruise around 20knots good luck with your project
 
"A displacement hull is like a

"A displacement hull is like a sailboat or trawler. your Shamrock is a planning hull.
I will copy my wiring diagram and convert it to a pdf file. Mine is a 1987 center console.

I saw a wiring harness I would use on eBasicPower.com. I would take one of the longer 10 0r 15 foor ones and cut it in to two pieces and use one on the console to the guages and one on the engine side to the sending units and ignition. there is a plug on each end.


Harness, Square to Square, 10´
Part Number: MAR6117-10
Weight: 1.9
Price: $29.95
Quantity in Basket: none

This is a Wiring Harness, 8-prong male rectangular plug male/female, 10'.
http://bpi.ebasicpower.com/c/ALL6I/"
 
You have no idea how much easi

You have no idea how much easier that makes things... like I was given the keys to the city! Thanks Robert.
I did check out that page but it was like trying to close up a brain surgeons patient! Well... maybe I overstated a bit~ but basically... yes! Its all Greek to me... just a bunch of wires!
I'll look up the item when I get back later today. If you're interested... I did take a few pics of the boat a month or so ago when I got it. I think I could post them since I have seen a few others.
ps~ bought that cylinder... from what I've read it may be more power than needed but hopefully the rest will be OK... who knows!?!
 
"Well, I see we solved an elec

"Well, I see we solved an electrical problem while I was out of town.

But really, I still have the same problem. Engine comes up to about 2200 rpms then sits there. It doesn't stumble or miss.

I'd like to hear from some carburetor experts. Could it be that the metering plate is warped? Both carb rebuilders I contacted were from California, said that Holley castings are junk. They offer their ('better than new') services for $165 to $300 (new is $363).

Is there a rebuilder in Florida?"
 
"Power returns!!!
What a reli


"Power returns!!!
What a relief!! Put the carb back on this afternoon. Engine started right up and ran smoothly. Then took it to the launch and went out to the bay which takes 15 minutes. The moment of truth!! Ran it up and planed right away. Recorded 23 knots. Highest before was 15 kts. I think the culprit was the "power valve". It's located inside the carb and it has a diaphragm in it. I think the diaphragm ruptured. I'm going to take the old one apart and see if I can find anything torn.
Thanks for any and all suggestions.
Regards,
Dave"
 
I took my Shamrock 20 with 302

I took my Shamrock 20 with 302PMC out today. It ran great. I got 3800 RPM out of it which is a new record. It would only do 3200 when I got it 5 years ago. I just put new heads on it.

Now to the cosmetics.
 
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