'73 850 Spider won't start

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Grubeguy
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Joined: Sun May 11, 2014 8:14 pm

'73 850 Spider won't start

Post by Grubeguy » Sun May 11, 2014 8:22 pm

I'm absolutely new to the Fiat world (my dad owned them when I was a kid but we never fixed the things together) and am going to ask a newbie question or two.

I've got a '73 850 spider that I did the body work on. I had the engine rebuilt and now that the paint job is done and drive train back in the car, hoses replaced, filters replaced, cap/rotor/wires/battery new, the car won't start. The starter will engage and engine will turn, I have gas through the filters and into the carb, but no spark.

What should I be checking for? Ignition issues are the obvious first place to look - spark from the coil and such, none of which I've begun with yet. Any advice or help would be happily received.

Miltonian
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Location: Milton, Wa.

Re: '73 850 Spider won't start

Post by Miltonian » Mon May 12, 2014 2:16 am

Are you CERTAIN that you have no spark at all? You can disconnect the primary coil wire from the distributor cap, hold the terminal about 1/8" from a solid grounding point, crank over the engine, and you don't get a spark? If so, there are quite a number of possibilities to explore, none of them particularly serious.

Before getting into a lot of possibilities, remove the distributor cap and have someone crank over the engine, to make sure that the rotor is turning, and that the center carbon contact on the cap hasn't fallen out, or there is water inside the cap.

You could have no power to the coil, bad ignition wires, improperly grounded points, fouled spark plugs, incorrectly set timing, etc. Shouldn't be terribly tough to diagnose. Good luck with it!
Jeff B.
1958 600 Multipla
1959 600 Sedan

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daled
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Re: '73 850 Spider won't start

Post by daled » Mon Jun 02, 2014 5:24 pm

remove the wire on the neg side of the coil.
turn the key to the run position and confirm that there is 12v on the plus side of the coil.

place one of the plug leads into the coil, install a spark plug in the other end and lay it on the block somewhere grounded.
use a lenght of wire attached to the neg post on the battery at one end, use the other end and bump it to the negative post on the coil. you should get a spark at the plug when the wire is removed from the neg post.

if no the coil is likely bad, if yes then confirm the following:
the battery is in the front of an 850 and the body is used for ground, this is a common problem, clean battery cable at both ends.
make sure body to block grouund strap is installed and is clean at terminal ends.

position on of the distributor cam lobes directly under the point set follower. check point gap is about .020". inspect point contacts, file using your wifes fingernail file if it necessary, and she ain't looking.
roll the motor over and make sure points fully close (point follower no longer touching distributor cam).
check that the wire from the points to the coil negative post is not broken or open.

reconnect the point wire to the neg coil post leave the distributor cap off and have someone crank the motor. a spark should be seen at the poinit set each time it opens and closes.

if we are good here then carfully inspect the rotor and cap for wear or damage. center post in cap must be in contact with the rotor at all times.

finally confirm good spark wires and plugs (replace with quality parts if necessary)
also i recommend that the condensor be replaced unless you know that its new.
71' 850 with (1.8L)
58? abarth 750
81' 124 (3.0L)

Grubeguy
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Joined: Sun May 11, 2014 8:14 pm

Re: '73 850 Spider won't start

Post by Grubeguy » Mon Jun 02, 2014 7:46 pm

I've more or less walked away from the thing until I receive a Pertronix pickup and coil. I've verified a good fuel supply and I'm not going to mess around with points or condensors. I'll be back in touch once the things are installed.

I appreciate the advice however.

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daled
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Re: '73 850 Spider won't start

Post by daled » Tue Jun 03, 2014 7:31 am

well if you like the black box, magic pick-up, computer processor metality, then go baby go.
but not me a coil, a set of points and a carburator, nothing simpler or more reliable. period...

good luck,
try to raise paul B. i think his beutifull 850 Coupe has a petronic thingy mabob on it.
71' 850 with (1.8L)
58? abarth 750
81' 124 (3.0L)

Grubeguy
Posts: 5
Joined: Sun May 11, 2014 8:14 pm

Re: '73 850 Spider won't start

Post by Grubeguy » Tue Jun 03, 2014 4:53 pm

I've got one of those spark lights - inline light that hooks up between the spark plug and its wire. When there's a spark, it lights up. I've got good spark on all 4 wires, and the plugs came pre-gapped (I've not verified it, shame on me).

As for an electronic ignition, nothing could be easier or simpler, in my book. They take the guess work out of points, adjusting the things, weak-or-not condensors, etc etc. I've got one in a '73 Mercedes, and it made a world of difference in how the car ran. I'm this shy of selling off that Fiat and buying myself a classic Volvo, because of all the hate and discontent that 850 has caused me. If a carb rebuild and electronic ignition don't cure what ails it, you'll see the thing on eBay.

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daled
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Re: '73 850 Spider won't start

Post by daled » Tue Jun 03, 2014 5:11 pm

i undrestand the frustration when teching out problems. ive ben banging my head on a 93 miata that the wife purchased...
i guess that im just too old, but i don't like it when i have to assume that a CPU (or many other black boxes) is doing its job correctly. yes there are test that may help point to a direction, but often 2 scopes, 4 multi meters, and the VIN matched software is required....CRAP i say, CRAP...

its ironic that you mentioned a volvo...i don't know much about the "classic" models, but my 2002 SC40 caused me more "hate and discontent" than any other vehicel i have owned... even more than my Truimp spitparts (oops thats spitfire).

well best of luck on the 850, ill keep an eye on ebay for a bargin :lol:
and happy hunting on the Volvo front, prehapse a p1800 is in your future or even a cool p120 !
71' 850 with (1.8L)
58? abarth 750
81' 124 (3.0L)

noah1
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Joined: Sat Jul 05, 2014 4:38 pm

Re: '73 850 Spider won't start

Post by noah1 » Sat Jul 05, 2014 5:43 pm

please post more info about the pertronix.
dist number and part number would be great.
installation probs/mods too please.
i have a marelli 140b and would like to go that route.
i am in close to the same situation and get spark but it is orange even though it will arc an inch(invisible but can be heard)still no start.
maybe someone could help me get this sweet ride running.
i am still a bit confused about the static timing/placing the distributor in the engine.
the dist was out when i got it.
i set the engine to 10 degrees btdc number 1 cyl ,points about to open,then turned over with timing light attached and it seems to want to start but at 10 degrees btdc not 0 degrees.
i cant seem to get the proper dwell even with just .008 gap it is still too low...20 degrees or so.
it has new points. could it be off just one tooth at the engine connection?
id sure like to drive this car some day.

also i am wondering about the setting of the cam chain.
do the dots on the pulleys line up on tdc cyl number 1 or cyl 4.
maybe both?
the book i have is very confusing and i believe a few mistakes.
on valve timing it says"intake opens at 16 brdc,continue turning till 0 degrees and both dots on pulley cams should line up.what the heck is brdc?
it also says,
...turn till number 1 cyl commences compression stroke and inlet valve is just opening.
i didnt know inlet valves opened on compression strokes.??!?

i have autobook
i have 2 850 spyders and neither run....yet
thanks in advance(10 degrees!!)
Kevin in calif

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daled
Posts: 369
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Re: '73 850 Spider won't start

Post by daled » Mon Jul 07, 2014 4:40 pm

brdc is probably btdc. - that's Before Top Dead Center
(text font may not be fully formed. typewriter generated and litho repro. (old school print issues)

remember 850 motors spin CCW.

bring no1 to TDC (no 4 will also be at TDC)
check valves at no1. both should be closed. Rockers should have backlash.
no 4 should have a valve open or just starting to open.
if you continue to roll CCW past TDC the intake on no 4 should be opening more and more.

set point gap at around .015 to .020 to start.
if you are using a 6-8 dwell meter make sure you are reading the 8 cylinder scale and then doubling the value

also check the rotation of the rotor. while rotating your crank CCW. and confirm that your plug wires are in the correct sequence (easy to get backwards if you are thinking "Normal car")
71' 850 with (1.8L)
58? abarth 750
81' 124 (3.0L)

noah1
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Joined: Sat Jul 05, 2014 4:38 pm

Re: '73 850 Spider won't start

Post by noah1 » Mon Jul 07, 2014 6:00 pm

Thanks for the reply.
i am using a 6/8 cyl dwell meter and may have cut the number in half instead of doubeling it but doubt it.
i changed the point gap from .018 to .008 the dwell stayed the same.
ill double check.
thanks again and good driving days to you!
kevin

Grubeguy
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Joined: Sun May 11, 2014 8:14 pm

Re: '73 850 Spider won't start

Post by Grubeguy » Mon Sep 15, 2014 4:21 pm

Update to my original - I've installed a pertronix ignition system and coil, and the car starts up, but refuses to idle at anything below 1500 rpm or so. I'm in search of an all-in-one procedure to set the carb (it's been rebuilt), for both the low and high speed circuits. All I've found so far is "adjust the mixture screw until it runs." Are the 30 DICA carbs REALLY that simple?

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daled
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Re: '73 850 Spider won't start

Post by daled » Thu Sep 18, 2014 11:39 am

This sounds like an air leak.

Check carb to intake and intake to head joints using a directed shot of carb cleaner. if engine changes speed then a leak is found.
double check any vacuum lines for splits and connection integrity.

make sure that the plunger in the intake manifold directly below the throttle isn't stuck in the down position or not wiggly and leaking air.

if your car is idling at 1500 RPM with no more idle screw adjustment, than you have an air leak.
if you still have idle screw adjustment but it dies if you try to adjust the idle down, this means that your low speed circuit is much too rich.
If you are dead-heading the fuel line to the carburetor, you must confirm that the delivery pressure is not overcoming the float. typically 2-3 psi max...
71' 850 with (1.8L)
58? abarth 750
81' 124 (3.0L)

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