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View Full Version : 351 wont fire up ...


rob935
03-07-2010, 04:43 PM
over the off season i had both heads skimmed on my 351 and replaced head gaskets etc. and torqued to specs , tried to start it up this weekend but with no luck at all . its turning over fine and seems to want to fire up but just doesnt start , i didnt remove the distributer when taking the heads off so the timing shouldnt need adjustment ?? any ideas guys thanks .

1redTA
03-07-2010, 05:01 PM
When diagnosing a motor that won't start, check for fuel air and spark
when you find out what is or isn't missing it will be easier to Internet diagnose

rob935
03-07-2010, 05:12 PM
its getting fuel and air but will have to check the spark to be sure .

thatsmrmastercraft
03-07-2010, 05:17 PM
its getting fuel and air but will have to check the spark to be sure .

You can use a timing light to check for spark. Its especially easy if you are working by yourself. Just put the inductive lead over a plug wire and tape or wire the timing light trigger in and look for the flash of the timing light.

Should be something simple. Good luck.

Laurel_Lake_Skier
03-07-2010, 10:24 PM
If the engine ran without problems prior to the work, I'd suggest starting with looking at things that may have changed while you were in the process of removing and replacing the heads. A compression check (it is possible the heads are not sealing or that by shaving the heads your valves may not be closing due to a need for shorter push rods or shims under the rockers) , vacuum test (if you have a leak between the intake and heads or carb and intake) and double check of fuel going to the carb would all be good starting points.

markismm
03-07-2010, 11:21 PM
I agree with the post above. Check first gas, then air, and finally spark. If you are receiveing these three items you should be getting some fire. If you have tried shooting starting fluid directly into the carb and you are getting no fire check the spark. While you can check it with the timing light, you can also check it by simply removing a plug and grounding the electrode and visually seeing if you are getting a spark. No spark most likely means you have a bad coil or have the cold wired improperly. You may want to check all of your wiring first.

Laurel_Lake_Skier
03-07-2010, 11:35 PM
In addition to the earlier post, be sure to double check the firing order.....its pretty easy to to mix up a couple of plug wires when everything goes back together and that of course will make it tough to fire the engine.

rob935
03-08-2010, 06:19 AM
thanks guys , i have checked all the wiring and its all connected correctly and plug leads are in the right order too , will need to double check for spark ....just wondering if its down to having the heads skimmed (valves not closing ) as i was very carefull to put it all back the way it was disassembled , i just presumed it would start up without any adjustment ???

CantRepeat
03-08-2010, 07:11 AM
How did you adjust the valves? If you have not done so, maybe the intake valves are not opening thus not letting fuel in. When you say it's getting fuel is that because you see it come out of squirters on the carb or are you pulling a plug and it's wet with fuel?

1redTA
03-08-2010, 07:30 AM
How much did the machine shop take off the heads? If the heads were skimmed to much to need pushrods the intake probally needs some attention too.

First ground a spark plug and make sure it is getting spark. As mentioned do you smell gas on your plugs? G/L

blackcreek
03-08-2010, 07:48 AM
I'm with laurel lake, check the compression. If you have a late model 351 and the shop took too much off the heads you will need shorter push rods or shims under the rocker plates. Do you know the amount they took off? You need to shorten the push rods by that amount or shim that amount under the rocker plates. Worth a look if you know the fuel and spark are working correctly.

TMCNo1
03-08-2010, 09:06 AM
Is the clip off the kill switch?

JimN
03-08-2010, 10:55 AM
The amount of material removed should only be enough to make the mating surface flat. Taking off more than .007" (IIRC) will raise the compression to the point that higher octane fuel may be necessary but it shouldn't cause the valves to stay open. OTOH, if I was taking the heads off for anything, I would freshen them up ie., valve job, cleaning, port & polish, etc. Also, any time a motor is torn down to this extent, the compression and timing should be checked before trying to run it.

Pull the plugs and make sure they're not wet. If they are, you don't have spark and this would also indicate that you have enough vacuum to draw fuel in. Use a timing light to check for spark, check the compression, vacuum and do a cylinder leakdown test if possible. If you don't have spark, stop cranking it with the spark plugs in place until you get reliable spark- continuing with them in will only flood the motor and some of the gas will get into the crankcase, which will dilute the oil and cause damage once it starts. Once you get it to run at all, change the oil to make sure it hasn't already happened.

east tx skier
03-08-2010, 11:40 AM
Is the clip off the kill switch?

I came here to suggest that. My money is on Harold's guess.

loeweb
03-08-2010, 11:56 AM
I came here to suggest that. My money is on Harold's guess.

I am going with you two as well. It's gotta be something simple that is being overlooked.

rob935
03-08-2010, 01:42 PM
How did you adjust the valves? If you have not done so, maybe the intake valves are not opening thus not letting fuel in. When you say it's getting fuel is that because you see it come out of squirters on the carb or are you pulling a plug and it's wet with fuel?

the valves werent adjusted at all , i just torqued the lifters to spec ?? fuel going to carb but havent checked plugs as yet ??

rob935
03-08-2010, 01:46 PM
I came here to suggest that. My money is on Harold's guess.

put your money away east tx , ive made that mistake before ......never again lol !!!

JimN
03-08-2010, 02:45 PM
the valves werent adjusted at all , i just torqued the lifters to spec ?? fuel going to carb but havent checked plugs as yet ??

How fast does it crank? If it seems abnormally fast, I doubt the valves are closing.

rob935
03-08-2010, 03:14 PM
How fast does it crank? If it seems abnormally fast, I doubt the valves are closing.

its cranking normally , doesnt seem to be any faster or slower than before ...??

thatsmrmastercraft
03-08-2010, 03:43 PM
its cranking normally , doesnt seem to be any faster or slower than before ...??

Probably not a valve / compression issue. Have you verified spark. I don't remember seeing that you had.

TMCNo1
03-08-2010, 04:40 PM
i didnt remove the distributer when taking the heads off so the timing shouldnt need adjustment ??

I am totally lost by this statement. You are saying, you didn't remove the distributor from the intake before you removed the intake from the heads, before you removed the heads from the block to have them worked on?:confused::confused:

rob935
03-08-2010, 05:11 PM
I am totally lost by this statement. You are saying, you didn't remove the distributor from the intake before you removed the intake from the heads, before you removed the heads from the block to have them worked on?:confused::confused:

thats right , the intake is shaped around the distributor and bolted off without touching the distributor at all ......

rob935
03-08-2010, 05:13 PM
Probably not a valve / compression issue. Have you verified spark. I don't remember seeing that you had.

no havent verified spark yet will try to have a look at that tomorrow evening ...

markismm
03-08-2010, 09:29 PM
I am totally lost by this statement. You are saying, you didn't remove the distributor from the intake before you removed the intake from the heads, before you removed the heads from the block to have them worked on?:confused::confused:

That is right. This is not a chevy. The distributor on a ford small block does not go through the intake. If goes directly into the block. It is easier to remove the intake after removing the distributor first, but it really is not too much of a problem to remove the intake without removing the distributor. In response to the original issue though, please let us all know as soon as you check the spark. Its a simple test that you can do in about five seconds to see if you are getting a spark and then you have one less issue to wonder about.

east tx skier
03-08-2010, 10:42 PM
put your money away east tx , ive made that mistake before ......never again lol !!!

Okay, then check the wires that hook up to the key. Had one come loose on me one time. Did the same thing. Crank, almost start, die. Worth a shot.

rob935
04-24-2010, 08:46 AM
hi guys sorry for the huge delay , i havent had any time to work on the boat until yesterday cos i cracked my wrist a while back and wasnt able to .......any way checked for spark and didnt have any on the 2 plugs that i pulled ?? checked all the wiring and all seem to be connected fine , cleaned down most of the connections and greased them up but still no spark . getting a meter to check the coil etc over the next day or so .

Jim@BAWS
04-24-2010, 09:15 AM
3 members have now suggested the KILL SWITCH...I am now the 4th

Jim@BAWS

thatsmrmastercraft
04-24-2010, 09:19 AM
You can use a timing light to check for spark. Its especially easy if you are working by yourself. Just put the inductive lead over a plug wire and tape or wire the timing light trigger in and look for the flash of the timing light.

Should be something simple. Good luck.

hi guys sorry for the huge delay , i havent had any time to work on the boat until yesterday cos i cracked my wrist a while back and wasnt able to .......any way checked for spark and didnt have any on the 2 plugs that i pulled ?? checked all the wiring and all seem to be connected fine , cleaned down most of the connections and greased them up but still no spark . getting a meter to check the coil etc over the next day or so .

Just a reminder of the simple way to check for spark without removing plugs.

Sounds like the consensus is its time to check the ignition switch.

rob935
04-24-2010, 09:21 AM
the kill switch has never worked in the time i have had the boat , will double check it and the ignition switch.

JimN
04-24-2010, 10:57 AM
the kill switch has never worked in the time i have had the boat , will double check it and the ignition switch.

I don't remember if you posted anything about checking voltages at various places. The first should be at the coil. If you turn the key ON and don't measure 12V at the coil, you'll need to work backward to find the problem.

83SuperSlot
04-24-2010, 01:58 PM
the kill switch has never worked in the time i have had the boat , will double check it and the ignition switch.

Definitely sounds like the coil to me... Since you were moving everything around doing the work you could also check the connections leading to the coil to make sure that they are all good.

Now that you have figured out that it is spark the rest should go pretty quick! Good luck!

rob935
05-10-2010, 03:37 PM
put the volt meter on it over the weekend , its reading between 7 and 8 volts at the coil with the ignition in the on position , pulled the ignition switch and it shows 12 volts here , checked all the connections again and retested with same results .....is it the coil or something else ???

JimN
05-10-2010, 08:25 PM
put the volt meter on it over the weekend , its reading between 7 and 8 volts at the coil with the ignition in the on position , pulled the ignition switch and it shows 12 volts here , checked all the connections again and retested with same results .....is it the coil or something else ???

Where did you ground the meter? All circuits should be referenced to the battery's ground post- not the cable clamp. If you still see low voltage, you have bad connections between the battery + post and the point where you're measuring the voltage. ALWAYS make sure the posts and clamps are clean & tight, the ends aren't those temporary bolt-on jobs and the ground connection on the block is clean & tight.

rob935
05-20-2010, 07:08 AM
replaced the coil yesterday but it didnt make any difference ...still no spark and im all out of ideas , i replaced the ignition module 2 seasons ago so it cant be that , im totally stumped !!!:mad::mad::confused::confused:

JimN
05-20-2010, 10:23 AM
i replaced the ignition module 2 seasons ago so it cant be that

Why can't that be the cause? It's electronic- it can fail at any time. Contact the manufacturer and find out if they have a list of troubleshooting steps for their module.

Remove the distributor cap and make sure the center electrode is in place. I have seen some caps that lost the carbon insert, once on my own car. Also, if you have no spark on any cylinder, try another coil wire to the cap- for some reason, I saw quite a few that went bad. For testing, you can use any kind of wire as a jumper.

Kyle
05-20-2010, 04:53 PM
I bet if you took the coil wire off from the dist cap and grounded it to the intake and there was spark then you would have issues with the module. If you took the coil wire off and grounded it to the intake and no spark jumped to the intake then you are not getting enough voltage to the coil since you have a brand new known good coil. Follow the wires from the coil back to the rear of the engine and check where all of the harness wires come together. Unplug and plug back in a few times. You may have some kind of corrosion that is causing low voltage or voltage drop. Do you have the 2 wires running to the coil reversed by chance. I believe that there is a purple wire and a grey wire. Check your Ground at the block and make sure it is tight and that you are getting a good ground there. Check your wires from the starter to the Breaker at the back of the starboard head. Make sure that all of the connections are tight there and that you are getting a 12v at the breaker. Find the wires running to the coil and follow them back to the breaker. Measure a voltage test at the breaker on the coil wires to see if you have a damaged wire running from the breaker to the coil causing voltage drop. 7 or 8 volts will not be enough to make the coil work continue chasing wires if I were you. If your safety lanyard is not working then take the wire that runs through the safety switch and cut it on both sides of the switch and crimp the wire together. The switch just stops current from flowing through that wire. If you connect the wire together then you will always be able to have current flow and bypass the switch.

JimN
05-20-2010, 08:31 PM
That gray wire is the tach lead- make sure it's not grounded- that's a cheap and easy way to kill any spark.

rob935
06-01-2010, 02:14 PM
thanks kyle , i took your advice and grounded the coil lead (end that goes to dist )to the manifold and got a spark .....i take it from your post that this would point to the ignition module ??? tried it the opposite way by grounding the end that goes to the coil but got no spark . i guess its the module so !!

CantRepeat
06-02-2010, 08:47 PM
thanks kyle , i took your advice and grounded the coil lead (end that goes to dist )to the manifold and got a spark .....i take it from your post that this would point to the ignition module ??? tried it the opposite way by grounding the end that goes to the coil but got no spark . i guess its the module so !!


I do hope you get it running.

Kyle
06-03-2010, 06:55 AM
thanks kyle , i took your advice and grounded the coil lead (end that goes to dist )to the manifold and got a spark .....i take it from your post that this would point to the ignition module ??? tried it the opposite way by grounding the end that goes to the coil but got no spark . i guess its the module so !!

I am not sure why you grounded the end that goes into the coil to the manifold, as that would do nothing.

I would leave the wire attached to the coil and take the end that goes to the distributor cap of the coil wire and ground it to the manifold. If you have spark then I would ground each wire one by one to see if you have spark. Make sure that the grey and purple wires are hooked up to the coil in the right spot. If you are not getting any spark to the end of the plug wires when you ground them one by one then its safe to say your module is bad. Make for sure that you dont have a cracked cap or rotor and make sure that they are not worn out. Inspect the inside of the cap before you just start spending money.

If you end up buying a module also get a new cap and rotor as they are cheap.

rob935
07-20-2010, 01:30 PM
it was the ignition module .... replaced it today , took 4 weeks to get the part from the states . first turn of the key it fired straight up , only ran it in the drive but may need to set the timing as it seemed to be running a bit rough .

rob935
07-29-2010, 03:37 PM
ok guys , i have the boat back on the water but its just not running properly . its fires up no problem , has oil pressure and temp is fine but its running really rough , just wondering if its just a timing issiue or has the machine shop skimmed too much off the heads ??

thatsmrmastercraft
07-29-2010, 04:09 PM
Back to rechecking all the basics. Verify that your timing is set correctly would be my first step. Your spark plugs may have become fouled - check a couple as well. Verify that you have the spark plug wires going where they are supposed to go.

rob935
07-29-2010, 05:34 PM
thanks , will check the plugs and get the timing checked too .

JimN
07-29-2010, 05:56 PM
thanks , will check the plugs and get the timing checked too .

I Agree about the plug wires going where they're supposed to. If the person who put them back on was thinking of another brand, the odd cylinders are on one side and the even are on the other, unlike Ford. Ford has 1-2-3-4 on one side and 5-6-7-8 on the other. Also, the firing order may be cast into the intake manifold, if it's original.

Covi
07-29-2010, 06:36 PM
Sounds to me like all cyliders are not firing. I too would check the plugs. Or with an insulated pair of pliers pull one wire at a time from the d-cap. if nothing happens thats your problem? if the boat start to bog down replace the wire and move to the next.

rob935
07-29-2010, 07:06 PM
i did all the work myself so all the plug wires are in the right places , also tried removing the plug wires with a pliers and found one of the plugs was mis-firing , replaced it and noted a big improvement . im now going to replace all the plugs and change the oil too (seems to be petrol in it from cranking over with dodgy ignition mod ) and get a timing light to check the timing .

rob935
08-25-2010, 06:26 AM
got the oil changed , new plugs etc , tried to fire it up but no spark again !!! looks like the new electronic ignition has blown !!!! any ideas on what might be causing the ignition module to overload etc ??? thanks for any ideas you may have guys .

JimN
08-25-2010, 09:21 AM
got the oil changed , new plugs etc , tried to fire it up but no spark again !!! looks like the new electronic ignition has blown !!!! any ideas on what might be causing the ignition module to overload etc ??? thanks for any ideas you may have guys .

Verify that it does or doesn't use the ballast resistor and set it up accordingly. Also, if the distributor ground isn't good, it can damage the EI module. The distributor grounds through the base- clean the area where the hold-down contacts the distributor base AND the motor. Twist the distributor and make sure it doesn't have a lot of dirt, etc around the base. If it does, clean it, lift the distributor and clean the area where it fits into the motor.