Hey there guys/gals, got a question, while driving to work a few days ago my car came to a powerless halt after rolling about 6 feet. I'm not sure what happened, this had happened once before and it required me to replace the Fuel Pump. The car this happened to is a 1984 z28, 305 V8, Carburated. Things that I've done in the not so distant past, that I wouldn't think would break are:

Replaced all sparkplugs with AC Delco replacements (About a month Ago)
Replaced all Plug Wires with Spark Force Plug Wires (About a month Ago)
Replaced Distributor Cap (About a month Ago)
Replaced Rotor (About a month Ago)
Replaced Ignition Coil (Yesterday)
Replaced Alternator (About a month Ago)
Replaced Battery (About a month Ago)
Replaced Starter (Yesterday)
Replaced Fuel Pump (About a month Ago)

And after all this, I'm getting spark, I've got fuel pumping, and she'll crank, but the engine WILL NOT START . Not sure what the heck is going on, but, I figured if anyone would it would be you guys. If I've left anything out, let me know.

Thank's
Adam

 

Exactly how does it behave?

Does it whirl over easily (too easily), then start backfiring out of the carb a time or 2 and get hard for the starter to turn, then pretend that it's almost going to start, then stop that and sound sort of normal, then get too easy to turn again for a while, and kepe going through a cycle like that? If so, you need a timing set.

Otherwise, try a set of new spark plugs. Have you looked at them? Do they look OK?

 

id say fuel pump cuz thats what my problem was, but since u have pressure, there goes that. have u checked yer ignition module? its under the cap, it can make the car not start.

remove it and take it to have it checked at yer local auto part dealer. if thats the case, make sure when u replace it, to put that little silicon underneath.

daniel

 

if you've got spark and fuel pumping, it sounds like it's time to check compression and timing chain. a compression test will show low also if there is a timing chain problem, but it is good for showing any other broken internals at the same time. i infact had my first LG4 break down from a bad timing chain. it never ran so good after i replaced that. all in all, i wouldn't say that's what is wrong, but it's well worth checking.

 

Everyone I talk to seems to think its the Timing Chain, and I wonder about the compression. Whats the best type of Timing Chain to get, and what do they run? And what do I use to check compression, and how much is the device? And what should my compression be?? Oh, and how big a job is the Timing Chain Removal and Installation? Thanks guys

Adam

 

Oh, and when you say timing set you mean timing chain right?
Just checking, cause I'm gonna go out and buy it all, might as well get it all in one fell swoop. Once again, thanks, and if you could give me a guesse-timiate on how much this is gonna run me I'd appreciate it.

Adam

 

You say you have fuel pumping, don't the carb'ed engines use a mechanical pump? If so, the cam is rotating, so the chain hasn't broke (assuming a mech pump).

Pull the #1 plug, since it's the easiest to get to, and spin the engine over as see if there's compression in the cylinder.

A clogged exhaust will/can mimic no/low compression.

 

Yeah, its mechanical, so.... damn.... its not the timing chain?? Hmmmmm, do you think the plugs are messed up or bad? And what do I get to check compression, and what does it cost?

Adam

 

we already know the timing chain isn't broken. he stated it had spark which means it is turning the distributor, not too quick are you. when a timing chain goes bad they rarely break, they just "jump" a couple of teeth over from where they are supposed to be lined up which puts the cam to crankshaft timing off.

 

Sword,

Remove a few of the easily accessible spark plugs to make sure they are not fuel fouled (wet). Dry off any wet plugs or replace them. Try starting again. If you get no firing at all, mark the distributor position relative to the engine and try advancing the distributor about 20°. If the engine tries to start, you may have slipped the timing chain. If you get nothing still, return the distributor to the marked spot and get a timing light and compression tester. Check the timing while cranking. The marks should be at least close to TDC (within 15°) while cranking. If so, pull all the plugs and test compression. You should get at least 90PSI on all cylinders.

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Are we a little snippy, Zippy? "Not too quick, are you?" may not be the most positive thing to add. We're all friends here. I can understand your point, since I miss some of the details in a lot of posts, too. (DOH! - I usually get them if I use my lips to read the second time around.)

You're right, most chains stretch and wear a whole lot before they break, and unless there has been a lot of high RPM use involved on a loose chain, it can go a long time that way. A compression test should reveal the poor compression from late valve timing if the chain has slipped. The ignition timing test should be a good indicator, too.

 

i'm just always this way, but my point for being annoyed was the reply as if everyone missed the fact that the cam is still moving. if your going to contradict other reply's then you are assuming that they are wrong. i also have no idea how he'd take the spark plug out and "see" if it has compression. compression isn't going to be a visual kind of thing and really in this case would need a pressure test since a "jumped" chain can still be close enough to allow compression, just not alot.

 

Hey zippy, keep in mind that the H.O. cars (L69) had an electric fuel pump even with a carb!
Anyway, back to the issue at hand, if you have spark, the cam is turning, as the distributor is being turned by the cam.
Now, on the fuel subject, how are you checking this? Are you just looking for the accelerator pump squirt in the airhorn? That should be enough to get it to at least try to start. (I just wanted to make sure you didn't go as far as to pop the line loose!) Also, if the spark plugs are wet with fuel, clean them with a torch, or even better yet, replace them again. They are pretty cheap.
Next, did it overheat? If it did, you could've warped the heads.
Next thing is the timing. Try moving the distributor, then a timing light as Vader described (he really does know what he's talking about!)

That about covers it all. There are 4 things that are needed to run a 4 stroke gasoline engine, they are: Fuel, compression, spark, and all of the above to be in time.

Good luck, and feel free to email with questions.

 

you said you had fuel pumping, can you look down the carb, actuate the throttle and see if fuel sqirts in.
if not, your float may be stuck.

if that checks out fine, check for jumped time like vader says.

if that checks out fine, undo the y pipe from the exhaust manifolds to make sure your exhaust (catalytic) isn't pluged.

do the simple stuff first.

 

Ah never mind, I'd rather take a dump

 

It was the choke somebody came over and check out the carb, shes leaking and the choke is pretty messed up. Its pretty cold in the morning and at night down here right now night.
And the choke isn't functioning, so I couldn't get it started. So, now I'm going out on Friday to get a new one, is a 600CFM Holley Carb w/ Electric choke good? And will it fit on my car?

Adam

 

ummmm, can I backtrack a little and change the fuel requirement to the proper fuel mixture for the conditions? LOL

I guess that's just one of those things that we don't think of sitting behind a monitor, but I know if I was actually there looking at the thing, I would most likely notice the choke not working right!

I had the same issue a couple years ago, and I just replaced the choke heater and it has been fine since!