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85 280 SL Hot Starting Issues

8K views 79 replies 19 participants last post by  nobby 
#1 ·
85 280sl...replaced FPR butha ing same problem. when attempting to start thecar..the starter stays engaged when releasing key in start process. walk away from car and 20 minutes it usually starts as soon as you turn the key...anybody have a similiar problem such as this. only started doing thuas after i got to florida.. suggestions please
 
#5 ·
The starter engages and spins the engine. However i let off start position the starter still spins for a few seconds. I wondering if i could have a bad fuel pump. I cant think of anything in the starter that could prevent the engine from firing.
 
#6 ·
ignition switch? put a test light on starter solinoid and see if power drops when you let off key. If it does not ignition switch could be problem. If power drops with switch turning off and starter still runs then soliniod is probably the problem
 
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#7 ·
I am sitting here waiting on the tow truck. Every time i turn the key the starter engages and spins the engine. That tells me the solenoid is doing its job and the starter spinning the engine leads to believe its not the starter. BUT when i release the key start position it still spins for a few seconds. The engine does not appear to be getting either fuel or spark.

I have to isolate which is at fault. Cont do it here in the parking lot, no tools, cant get under the car. I should be back at my house within the hour. Ill pop the hood and use a small floor jack to see if i can get under the ear to see if the fuel pump is clicking when key is turned on..
 
#9 ·
The starter soliniod has two functions it engages the starter when triggered by power and it disengages the starter with spring pressure when power is lost.
check for power when key gets turned off
 
#8 · (Edited)
On my car the starter solenoid is wired via the neutral safety switch to the ignition switch start position. The FPR uses this as an input signal to activate the pump in the absence of RPM pulses.

The starter solenoid closes a switch that powers the starter moter directly from the battery. For this to happen the solenoid is either is powered or the springloaded plunger stuck.

I have attached the wiring diagram for my car.

Maybe I have misunderstood your problem, thought the problem was that the starter continued operating after the ignition key was moved from start to normal. If you can't get the car started, then FPR could be faulty, if so I would connect a line from the +12V battery to the white/red line on the fuelpump, you can get to it from the rear without jacking up the vehicle.

Good luck !

Alternatively you can bridge the FPR pins 30 and 87.
 

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#11 ·
After waiting 3 hours, the tow truck arrives. Tried starting the car every 15 minutes.
Driver positions his truck to drag car up on flatbed. Get in insert key to release front wheel lock sterring wheel and the fuckin car starts up.

I drove it home, no issues. Park in garage and restart the car 3 times.

There is a florida gremlin in this car !!!!!
 
#14 ·
Today i started "maggie lass" and being a nice warm day, i took her for a ride. Stopped in a local Sonic and bough a milk shake. I did not shut the engine off for i haven found the gremlin in my engine as of yet. Got my shake and made a tour of the area. I had heard there was a great flea market and i found it. Was home after about 1 hour. Pulled into the garage and shut her down. 10 min later i turned he key and she started. 45 min later
I turned the key and same ole shit. Engine spins but no fire. Tried it 4 times. I raised the hood and it was very warm. So I sat on my USC school chair with my thumbs up my ass taking in the problem. I couldnt ear the fuel pump clicking. Hell im hard of hearing anyway.

So I let her be and finished a cornice Im building to cover my lanai sliding glass doors in the
Living room. Got it finished and painted. Ready to install but i need some angle brackets.
Took the golf cart to Home Depot and returned. Its been a good 4 hours so i reached in and turned the key and "maggie lass" fired rite up. My daughter arrives tonite and will be here thru next tuesday so ill have her assist me by turning the key on a no start time and see if the uel pump is clicking or/ and ill pull a plug wire to check for a no spark issue.
 
#15 ·
I just wrote the check and mailed it to Calif for my 2015 Taxes. I got hit on sales tax on my house i sold for 631k so im crying in my vodka tonite.

But next month im buying a lift of some sort to git the Benz up so I can get underneath.
By then the guys buying the lifts on the garage lift thread should be able to provide info
On which one to buy. Yes, ill be getting one that lifts 5000 lbs.

So If its the fuel pump then ill wait until I get a lift to get her up in the air.

And by the way I have seen more than a dozen 107's here in the villages.
There a couple that look really good. Theres a 450sl in the villages classifieds that
Is advertised for 14k. Its yellow.!!!!
 
#16 ·
Be interesting to test if you have Spark when you crank the times it won't start.
If you have spark, then I would suspect a fuel problem.
If you do not have spark, I would suspect electrical.
 
#19 ·
Dennis, I believe you have two problems now, one caused the other to appear.....

Your original problem was the car would not always start, causing you to crank the starter over and over again......... resulting in the starter hanging up for several seconds after you release the key.....

As stated previously, there may be a miss-adjusted or faulty safety switch causing the ignition to not energize......................

As far as the starter, it could be the starter motor is drawing too much current that it tries to weld the solenoid contacts closed.........

Or the plunger or pinion shaft are sticking causing the contacts to remain closed until the vibration shakes it loose...

Or the starter was not shimmed correctly when installed and now the pinion gear is getting stuck while engaged with the flywheel ....

None of which sounds like fun...........

Or it could be the ignition worn and sticking...... :(

Just my 2 cents worth.....

On a brighter note, the snow is starting to melt away AGAIN here in Michigan............ :)
 

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#20 ·
I've read several postings about "shims" for the Starter and wonder if that is the
reason my Starter makes an unusual noise on startup. Sounds like the plunger
part is not releasing quick enough. Maybe its just a weak release spring or maybe
needs to be shimmed up. In any case, it starts up with no problems.
 
#21 ·
If the neutral safety switch is not aligned, the starter would not crank at all, see wiring diagram.
I am av bit sceptical to the solenoid contacts getting welded by the 80A starter current, the disconnect spring is very strong, the solenoid draws 9A to overcome the force. The starter current reduces with rpm.
The solenoid has a rubber seal that sometimes split with age. This could cause plunger rust.

The starter shim adjusts the pinion gear relative to the flywheel ring gear.

There is an inspection panel at the bortom of the automatic transmission where you can check the ringear wear and possible misalignment of the pinion.

The starter is only fixed to the transmission with 2 bolts, beware that one connection is directly to the +12v battery.
 
#22 ·
Hey Guys, i really appreciate all the great comments. I am still in a testing fuctional stage on what to do. This weekend it rained off and on here in the villages florida. So I am building cornice boxes over my sliding glass doors in my new house.

Over the 2 days (sat & sun). I must have started the car a dozen times (sitting in the garage, cold engine). Not one time did the car fail to start as soon as the starter engaged.( i mean immediately started). No cranking just turn the key to start and varoooom. Im standing outside the car reaching in and turning the key.

Today after returning from playing golf im going to take the car for a warm up ride. 10/15 miles and back and park it in the garage and let it sit for 10 minutes and then see if it will start. I will be listening for the fuel pump to click before i engage starter. I shall report the results.
 
#23 ·
Wonder if something is getting heat sinked and causing an intermittent problem. I had an issue where if I tried starting the car but the starter didn't engage the ring gear the starter would get stuck on and run away without cranking the engine. Putting shifter into gear would shut that shit down. I would start by cleaning grounds. A burned contact can also give you weird issues, when a switch turns off there as a little arc which burns the contact. Good luck Dennis!
 
#28 ·
Yesterday i again did some driving in the car. It started on the turn of the key. Made a 15 mile drive around the area. Car idles fine at stop lights (600 rpm). Takes off and shits and gits down the road...bring it home put it in the garage and 20 minutes later it dosent fire.

2 hours later it starts with the turn of the key. Re- Read all about the K-J and have ordered a new acumulator and filter (thanks to Dave & rowdie for part #) from autohaus.

I thought I was a pretty decent mechanic but this florida gremlin Is making me doubtful about my skills. Unlike Nobby Im in not going to sell the car just yet. This may have me begging for mercy, but it will get solved....eventually.

All my logic and common sense tells me that it isnt any part of the starter, but probably
A fuel related issue. We shall see !
 
#33 ·
Have you tested any thing yet? Let us know what was tested and what the result was and we can try to steer you in the right direction.:smile
So far sounds like we are only going to discuss the problem then start throwing parts at it. New parts are nice but it might be cheaper and faster to pay the dealer to check or fix it.
 
#34 ·
Well, ive installed a new fuel acumulator and a new fuel pump relay, and I still have the same problem. Took the car for 25 mile drive. Ran great, idles great at all stoplights,
Gits it on down the road thru all five gears. Pulled into the garage, shut her down. Cleaned up my tools and put then away.

15/20 minutes turned the key and the car dosent fire up. Engine cranks just fine.
Ill wait 20 min or so and try to start it again.
 
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