Author Topic: new parts-wont fire  (Read 5674 times)

tbarrie

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new parts-wont fire
« on: April 03, 2009, 00:06:28 »
I put a new voltage regulator and a rebuilt bosch 35 amp alternator along with a new optima red top battery on, and low and behold- it doesnt want to start!  It tries to turn over, but sounds like the starter is not catching/firing.  You'll hear the whannan-nanna followed by an attempt to fire, then if I continue to cranck on it multiple attempts but it doesnt turn over.  Any ideas?
            Taylor

J. Huber

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Re: new parts-wont fire
« Reply #1 on: April 03, 2009, 00:25:58 »
Taylor, so it sounds like it is turning over but not catching? wonder if its fuel related? what is your technique as far as fuel delivery? Reason I ask is, there is a tendency to give a lot of fuel when hardstarting. Like flooding a carberator -- it can keep the car from catching. One trick was to actually remove the fuel pump fuse (#4) and try cranking. Another is to use starting fluid -- I don't recommend this unless you know what your doing... If it is fuel related, things like a leaking Cold start valve or even a dead Thermo Time Switch can keep a car from starting right.

Couple other questions: are you still using points? If so, whats their conditon? how are the plugs? coil and resistor? You have the big ignition components handled, but don't overlook the smaller ones.
« Last Edit: April 03, 2009, 00:40:31 by J. Huber »
James
63 230SL

jeffc280sl

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Re: new parts-wont fire
« Reply #2 on: April 03, 2009, 00:37:06 »
Taylor,

Its unclear to me from your explanation if the starter gear is engaging with the fly wheel consistently.  Is this what you mean when you say it sounds like the starter motor is not catching?  If this is the case you may need to clean the gear assembly on the starter.  As the starter turns, centrifugal force causes the gear to extend and meet the flywheel.  The gear is spring loaded so that when you stop cranking the starter the gear returns to a retracted position.  Your gear may not be extending properly due to dirt or some other obstruction.  Just and idea.

tbarrie

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Re: new parts-wont fire
« Reply #3 on: April 03, 2009, 01:11:27 »
J.Huber-  1st off, it has mechanical fuel injection, new points and coil/resistor,  I know that the plugs and wires are rather old  the cold start valve has bee wired to the washer relay so that i can acctuate it manually- had/have a problem starting when cold and especially in rain, and it has always idled high though it varies +/- 500rpm in different weather(hot/cold) I know, a lot to wade through.  Even with all these problems I have always been able to get it to start, sometimes I have just had to crank for a while till all cylinders would catch.  I am going to try plugs and wires next followed by coil and resistor if the pulgs/wires dont work.  any other advise I would love to here, if there is any other info you need just let me know.  Thanks

Jeff- Is there an easy way to get to the starter gear to check/clean?  There is a lot of build up from an old oil leak coating nearly everything under the hood.  Before I inherited the car it had/still has some oil leaks that I am in the process of remeding, it might be part of the problem as you said with the gear engaging. 
What I meant by not catching is that you will hear the started "whiring" ( I dont mean the noise from the fuel pump) and trying to turn over the engine.  After a second or two it feels like somewhere a cylider is tryong to fire, but never gets enough momentun/spark/fuel? to turn the crank and start.  It has always had similar symtoms just not as severe and with a little creative pedal work and continuous cranking it would start.  again, any insight would be greatly appriciated-
  Thanks
                                 Taylor

ja17

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Re: new parts-wont fire
« Reply #4 on: April 03, 2009, 03:54:56 »
Hello Taylor,

Sounds like you spark plugs are fouled.  Find some good non-resisitor spark plugs. Try NGK BP5es. You can check the spark plug wires and ends with an ohm meter. I hate to see nice original wire sets scraped for no reason. Ignition contact points sometimes tarnish from long storage.

If your engine has air, fuel, spark on time and compression it will run.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

psmith

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Re: new parts-wont fire
« Reply #5 on: April 05, 2009, 06:16:04 »
Taylor,

I think you misunderstood J.Huber comment.  What he said was "like flooding a  carburetor" (italics added)  He has had his car for over 30 plus years and has been through the same problem you are having.  My car has been running fine for some time now but recently developed a hard starting problem too.  I am going to look at the Cold Start Valve and the Thermo Time Switch and see if that's where the problem is.  Also, you mentioned that you replaced the points and resistor.  There are several different resistors used and it's not uncommon to get the wrong one.  Just for grins, put the old one back on and see what happens.

tbarrie

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Re: new parts-wont fire
« Reply #6 on: April 05, 2009, 15:52:51 »
Wanted to let everyone know that she is running strong again, new plugs and an adjustment on the fuel injection and she fired right up.  Thanks to everyone for their knowledge and help. 
 
 I know that it is still running rich, I am looking into the thermo time switch.  I have the cold start valve hard wired from the wiper squirters so I could manually actuate it, so though I know it is bad it only operaters when I want it.  ( was having a very hard time starting in the cold or when it rained, a mechanic who knows these cars well suggested it as a quick fix)  My baby is old and has her quirks but I love her  ;D

ja17

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Re: new parts-wont fire
« Reply #7 on: April 05, 2009, 21:23:15 »
Hello Taylor,

Glad your back on the road.  The fact that it starts hard when it rains, tells me you have a weak place in the ignition system. the damp air causes a weak or no ignition spark.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback