chrysler 707hf starts easy dies in 30 seconds

hello to all you boaters that love to get good but old things working again,
well, i'm baffled. when i was buying this chrysler sport satellite boat 3 months ago, we did a test ride and though motor was hard to start, it ran strong and smooth for the next hour or so of testing, so i bought it.
the hard starting i fixed by replacing the choke solenoid(was sticking open and closed), replacing the battery terminals(rusty, intermittent), and cleaning all the ground connections(don't know if they were bad, just good idea from what i've read on posts)
using a 150 gallon water tank with water inlet ports covered by water, i was able to start easy and test run at 1000rpm and run it up to 3 or 4 thousand rpm off and on for 30 minutes total time, occasionally putting it into forward and reverse. seemed to me that all was perfect. so, i stopped working on the engine and had fun ordering cushions, boat cover, tach, seats, fun stuff for the next ten days.
and on the eleventh day, i returned to the boat and lowered the engine from it's tow tilt position to into the water tub and started it up which it did easy on first try, and motor ran smooth for about 90 seconds like before(i had a big smug smile on me that i fixed the starting problem so well ) and it died.
what the heck? i waited 5 seconds, hit start, started easy and smooth for 60 seconds and died.
well, to keep it a little short, dispite a new cd unit(had and have good spark), gas from tank comes out good from hose going into the fuel pump, fuel filter on side of pump is clean, spraying started fluid when it's dying, pumping fuel bulb whole time, new fuel mix in tank, watching one spark plug wire sparking an external plug while it's running for 30 seconds(starts easy even with only two of three cylinders hooked up), it still won't keep running more than 10 seconds or so now.
i'm baffled as to how in ten days i went from perfect start and run to start easy and run only 10 to 30 seconds.
so, if anybody has any ideas as to what has happened to cause this to happen, please let me know.
was so happy, proud and now sad disappointed in my ability to fix things,
christo555

Re: chrysler 707hf starts easy dies in 30 seconds

My old 1973 85hp was sparking and would fire up with some gas mix sprayed in but had been sitting for years so I knew it needed carbs rebuilt, fuel pump, etc. After doing those things she fired in the driveway and purred like a kitten for about 15sec then died. tried choking, spraying in fuel mix, all that stuff but was only able to get her running very briefly a few more times. Saw I had no spark hmmm.. Checked the points, they looked good, clean, smooth, like new. So I went on a probably 6-8 hr quest of checking wires, connections, dissembling ignition switch, CDI check, coil, blah, blah... Frustrated, I decided to start back at the beginning. This time I sanded the points instead of just checking the gap.... FIRED right up... I felt good but pretty stupid..

Moral to story... "KISS", no offense but the old saying of "keep it simple stupid"...Its probably something super simple.. Do you have a manual like a Seloc?

It comes down to a few things normally..
1-Checking and having good even compression is a must..
2-If you have good spark then its a fuel issue. If no spark or erratic spark then its electrical of course..

They make a cool little thing that you can get at auto parts or Harbor Freight called a "spark checker". Basically it goes inline with a spark plug wire and it makes it real easy to see if you're getting good spark, check each one..

Good luck...

Re: chrysler 707hf starts easy dies in 30 seconds

snwwlkr
thanks for the reply. i've ordered three carb kits since my post and am ready to rebuild them. when i took the bowl off the first of three carbs, there was a reddish sludge/grit in the bottom of the bowl, about the area of a quarter. i was happy to see this as i though it was the cause of my no run after easy start.
but after reading your post, maybe it's the points!
i don't understand how the points could cause my problem, but your problem does sound like mine.
i'll let you know what happens. have to hurry, it's getting cold around here already.
christo555

Re: chrysler 707hf starts easy dies in 30 seconds

Starting easily and dying soon after is almost always a fuel issue. Given that you already know there is varnish in the carb bowls, it is a good bet that after starting on choke, it is running out of fuel.

Disassemble the carbs and clean all passages with WD 40. Use a pipe cleaner for the small brass idle tube and the low speed needle passages. Do not use any wire to clean the metered orifices behind the butterfly.Pay special attention to the inlet needles and seats and set the float level correctly.

Re: chrysler 707hf starts easy dies in 30 seconds

Franks the guru here so read a lot of his stuff, and others.. Learn a lot in return...

The point is, no pun intended.. Its usually something easy, even rebuilding the carbs is pretty easy... having a repair manual is almost a must though for doing much of anything with the motor and having some reference... You just have to cover all the common basics and it doesn't take long and you'll know your way around the motor and its little hicups in no time.. Points are just another example of how simple it can be.. Just like Franks saying about spray some WD-40 etc thru everything. Doesn't take much to go from running like crap to purring like a kitten... Mines been a blast this summer. Been to the lake at least 15 times and other than a little problem on the first test run(still got me back to the ramp) its got me home with a smile every time.

Good idea if in doubt at all to replace all fuel lines, rebuild fuel pump and carbs..... Note---Put a clear automotive type inline fuel filter right before the carbs.. It'll keep any new crap from getting back in the carbs.. If poor as a church mouse you might get by with cleaning everything as long as it still looks in decent shape. Its just easier to do it once, and right the first time then you know its done and mark that one off the list

Re: chrysler 707hf starts easy dies in 30 seconds

thanks to both Frank and Snwwlkr for the help. i'm going to do the carbs first and see what happens. if no fix, then i'm going to clean the points. we'll see what happens.
christo555
ps: if i don't use wire to clean the orifices behind the butterfly, how will i get the varnish out?

Re: chrysler 707hf starts easy dies in 30 seconds

soak in cellulose thinners and blow with compressed air.

Re: chrysler 707hf starts easy dies in 30 seconds

Those are metered orifices specifically sized to meet the fuel requirements of that engine at various speeds below that at which the main venturi starts to deliver fuel. If you use wire to clean them you run the risk of enlarging them. This will upset the balance of fuel to air at low speeds.

To clean, you remove the low speed needle and inserting the red tube that comes with the spray can squirt a couple of good shots into the cavity. If it flows freely out the holes, they are clean. If it does not, then use a stiff bristle or a toothbrush to open them. If that fails, then you must remove the welsh plug from the top of the carb and clean the cavity.
This is really almost always unnecessary though. WD 40 seems to clean out all but the most stubborn varnish.
The only carb I have had which would need the welsh plug removed was corroded so badly that I threw out the carb anyway.

And yes, I forgot to mention: Like snwwlkr said, insert a cheap inline fuel filter between the pump and carbs. This will remove any crap that the pump may shed. Use a new fuel line between the pump and carbs.
You need to be vigilant here because if a piece of junk gets through and clogs only one carb, the other two cylinders will carry the engine while the clogged one goes lean. The piston serviced by the clogged carb will melt. A cheap fuel filter and new fuel line will prevent this and save many dollars over their cost.

Re: chrysler 707hf starts easy dies in 30 seconds

well, i took the carbs apart and found that the bowls had some reddish reddish very fine something in them. took a pictureView attachment 119980View attachment 119981 . i don't know if this amount is normal or what it is. my guess is that since the 6 gallon tote tank is the original unit made of metal, about 35 years old, that the stuff in the bowls is rust from the tank. i did check the filter in the tank and on the engine and they looked clear, but maybe this stuff is fine enough to get through the filters but still make the carbs not work right.
the carb rebuild kits that i got from iboats have the wrong size gaskets on each end.(sierra 18-7037) which even sierra says are correct for my chrysler 707hf engine.
so, don't know what to do at this point.
thanks again for helping me figure this out. sort of like csi for dead engines.
christo555

Re: chrysler 707hf starts easy dies in 30 seconds

Hmmm. Pretty sure thats the right kit. When you say "on each end", are you talking about the gasket betweem carb and the intake, like on the motor side of the carb and the one on the opposite end like for the air box thingy? That kit is what I used on my 1973 85hp and my 1971 70hp parts motor looks just the same. What are the numbers on the carbs? and are they all basically the same. Numbers may differ slightly thats ok... My kit had stuff in it I didnt need or just extra stuff depending on your exact carb I guess.

A little crud in the carbs like your pic is not that bad, not good but could be way worse. Sometimes it can be like someone put a spoon of tar in each bowl on a motor that has set for a long time. Think clinical clean when working on them. A tiny speck of trash like Frank said can clog up a jet. Blow out everything with carb cleaner or wd-40, carbs and carb parts, fuel lines...Rinse out all of the old gas in the tank and derust the tank if necessary. Dont forget that inline filter... You'll regret it if you do..

If you're from Basalt CO isnt boating about to come to a screeching halt???

Re: chrysler 707hf starts easy dies in 30 seconds

Snwwlkr,
the air horn and block gaskets are too big by an inch or so. the carbs all have the same numbers: WB8D 14 and 333061 3 engraved on them. they look original for my chrysler 707hf engine.
i'm sorry that you think the crud in the bowls wasn't too bad. to me that means that the carbs are not my problem. then, i have to hope it's the points which frank doesn't think is the problem.
but, as you pointed out, it's getting cold here. ruedi reservoir in colorado got 6 inches of snow last night. but i can still work on the engine for awhile and have it ready for next summer.
thanks for the input, christo555

Re: chrysler 707hf starts easy dies in 30 seconds

From what I saw in the bowl pic a good cleaning would possibly suffice. It never hurts to do a rebuild though. Did you say if you have a repair manual? Also, proper setting of the floats is critical.. repeat.. critical..

Points are easy.. Have you checked them?.. The Gap? and also you can check continuity..

Something surely sounds wierd about the gaskets being wrong. I'm in the middle of moving and my motors and book are in storage but pretty sure WB8D is a standard carb and that carb kit should work.. Maybe someone else will chime in. If not I'll get to my stuff here asap..

Re: chrysler 707hf starts easy dies in 30 seconds

sounds like same problem i had i used champion spark plugs then changed to nkg or nfg or something like that and saw a huge performance difference
oh yes and the float in the bowl should be levelwhen held up right and upside down there should be 1/16" gap between float and jet.

I have book with tune up and overhauls.

my cousin the mechanic solved the spark, or lack of running right for me. the right make of spark plug genious.