2024 Canadian Poncho Calendars are Now Available! CLICK HERE

 

 

Members Login
Username 
 
Password 
    Remember Me  
Post Info TOPIC: Help diagnose my engine


Poncho Master!

Status: Offline
Posts: 1740
Date:
Help diagnose my engine


I have seen the pickup coil wires break without breaking the insulation and the vacume advance will pull them apart. The engine dies for a split second and then the wires touch and then not and so on. Causing a crazy bucking. Disconnect the vacume advance and drive it. If the bucking is cured, change the pickup. Good luck.



-- Edited by jc on Wednesday 11th of July 2012 10:35:22 PM

__________________

'68 Parisienne 2+2 Convertible Matador Red (Resale Red but not for sale).



Poncho Master!

Status: Offline
Posts: 2530
Date:

Ok Thanks guys ! I have a spare fuel pump that I will try and will also try disconnecting the vacuum advance to see what happens ?

Slowly everything is fine ...



-- Edited by pontorquer on Wednesday 11th of July 2012 10:31:39 PM

__________________


Poncho Master!

Status: Offline
Posts: 2530
Date:

First the good news : I'm gonna be a grand papa ! My 21 yo son and girlfriend are expecting a baby, I found out last night ... Secondly I got my 75 Grand Am back on the road today ! I worked on it for the past couple of days, I replaced the accelaretor pump and inspected/cleaned the guts of this 75 Qjet, sure helped. Also, I replaced the HEI coil in my distributor. The problem is when I drive on the highway at let say 60 mph and stump on it, the engine bucks violently and I get a backfire through the back, It started doing it at the end of last summer ... To me it's like the ignition is not keeping up with the higher revs, so not burning the fuel properly in the cylinders. The engine is a Pontiac 400, could it be the vacuum advance or module, maybe the pickup coil ??? Help Please  



__________________


Canadian Poncho Superstar!

Status: Offline
Posts: 4508
Date:

That or maybe not enough fuel delivery - too lean, fuel pump, etc .



__________________

62 Catalina 2 dr post project

69 Parisienne 2 dr ht 427

55 Bel Air 2 dr post 265PP/PG

68 Bel Air 2 dr post BB project

 



A Poncho Legend!

Status: Offline
Posts: 48633
Date:

Do you not have another car you can swap the distributor from? That would eliminate that possibility (or confirm that is the problem)

__________________

1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars



Poncho Master!

Status: Offline
Posts: 2530
Date:

Guess I could do that as I got 2 other spare HEI distributors ... lol. First I have to try the plug the advance trick just to satisfy my curiosity ... I know, Process of elimination with these old cars ...



__________________


Poncho Master!

Status: Offline
Posts: 2530
Date:

Tonight I plugged the vacuum source for my distributor advance and put the timing light on the balancer just for the heck of it, at first it was pretty steady at 8 BTDC where I had it set last summer then, all of the sudden the mark fell down at least 2 " off the timing mark tab BTDC so there is definitatly something wrong with the distributor, the engine had this rubbing sound like when it's off timing and yes the retaining bolt on the distributor is real good and tight. Could it be a bad distributer shaft ? By the way what's this rubbing sound when the engine's out of time ?



__________________


Canadian Poncho Superstar!

Status: Offline
Posts: 7176
Date:

how much slop is in your timing chain?  take off the distributer cap, watch the rotor and rotate the crank by hand, Clock wise and counter clock wise..

a sloppy chain should show this way, if there is a lag when you rotate...



__________________

later...rog

AADD supporting member !!
I'm a collector...not a builder!!Located in sunny central Saskatchewan at the lakehead!


Poncho Master!

Status: Offline
Posts: 2530
Date:

Hmmmm ! Sounds like a combination of worn out engine parts, maybe it's time to yank this tired engine and install the 455 ... I was hoping to drive it a little more and enjoy the summer cruise.  



__________________


Canadian Poncho Superstar!

Status: Offline
Posts: 7176
Date:

I e also read that Chevy hei coils are not the same as Pontiac hei coils? They have differnent coloured wires, and will act sonny at higher rpms? Anyone????

__________________

later...rog

AADD supporting member !!
I'm a collector...not a builder!!Located in sunny central Saskatchewan at the lakehead!


Poncho Master!

Status: Offline
Posts: 1833
Date:

HEI's are well known for sticky mechanical advances. Check to make sure the weights swing in and out easily and smoothly.

Your misfire/big then back fire on hard acceleration sounds like a leaning out problem. Is the new accelerator pump working properly? Is this happening when the big vacuum secondaries open up?

__________________

_______________________________________
==|====|----B-E-A-U-M-O-N-T----|====|==

\__________________|________|____________________/

__\____O__________________|66BEAU|___________________O____/



Poncho Master!

Status: Offline
Posts: 2530
Date:

Started process of replacing my timing chain tonight and distributor ... I got everything off in a couple of hours without any issues, how lucky I was compare to Todd ie. no seized or broken bolts, the chain needed replacement, she's pretty loose about 1/2 inch play. Got to clean the cover and parts now soo many years of yucky oily grime, all automotive fluids where covering my hands, I love that dirty mechanic work ! lol 



__________________


A Poncho Legend!

Status: Offline
Posts: 26765
Date:

I'm glad to hear you didn't experience the grief I did!

__________________

Todd
Site Founder

Like us on Facebook. http://www.facebook.com/CanadianPoncho

Canadian Poncho World Headquarters - Prince Edward Island

 



Poncho Master!

Status: Offline
Posts: 2530
Date:

Ok, today the car is back on the road ! I was gone on holiday for 3 weeks. So what I did to the engine : I replace the timing chain, the fuel pump, accelerator pump on the Qjet, distributor, bunch of vacuum hose, balancer, timed the engine and ajust the idle mixture screws with vacuum gauge got it up to 16. Then after all this was done I took it for a drive on the highway, floored it and still acted up around 80-90mph, heard backfire threw the exhaust so the only thing left I'm thinking is the carb, definatly fuel lean starvation ... 



__________________


Poncho Master!

Status: Offline
Posts: 1833
Date:

Start checking fuel delivery system. Fuel pump, lines, filter (in-line and sintered), also check jets and float levels.

Actually, you've done a ton already with no success. Maybe it's time to do some diagnosis rather than just replacing stuff. Can you hook up an exhaust gas analyzer you can leave active while you take it for a drive?



__________________

_______________________________________
==|====|----B-E-A-U-M-O-N-T----|====|==

\__________________|________|____________________/

__\____O__________________|66BEAU|___________________O____/



Uber Guru

Status: Offline
Posts: 3932
Date:

Also check to see if you back barrel's air valve is opening. They can get sticky over time and not open. There is a small set screw that sets the spring pressure on the valve. You can set it to open earler or later depending on how much spring pressure you have.



__________________


Poncho Master!

Status: Offline
Posts: 2530
Date:

Thanks guys, tonight I filled the beast up with 77 liters of mid grade gas and she was working alot better, I only put 20$ of gas twice prior to this,  tonight she worked alot better ... WOT at 90mph and no backfring :) but still not quick and peppy enough ... lol. It must have been old stale gas and stabil left in the tank after winter storage, doesn't take much to throw these old Qjets out of wack ...



-- Edited by pontorquer on Thursday 23rd of August 2012 10:36:26 PM

__________________


Poncho Master!

Status: Offline
Posts: 1833
Date:

Gas today is horrible. It must be the ethanol that causes the gas to break down. I plan on leaving my vehicles (car, boat, motorbike, lawnmower etc) full of premium (with no ethanol) plus some Stabil. I had to strip carbs and fuel systems on the boat and motorbike this spring to get them to fire up. They still didn't run well until i got through a full tank of gas.

I should have thought to ask about the gas. Glad it's getting better!

__________________

_______________________________________
==|====|----B-E-A-U-M-O-N-T----|====|==

\__________________|________|____________________/

__\____O__________________|66BEAU|___________________O____/



Addicted!

Status: Offline
Posts: 114
Date:

I understand that Petro-Can Ultra 94 has no ethanol either.  True?  What ever, I use Shell premium in EVERYTHING.



-- Edited by Keith Tedford on Friday 24th of August 2012 09:50:16 PM

__________________
Keith Tedford


Poncho Master!

Status: Offline
Posts: 2530
Date:

I read on other forums that stabil ain't that good either ? I stay away from Mohawk or Husky, they use alot of Ethanol crap ... Any good gas suggestion in Winnipeg MB ? Coop Ok ?



__________________


Guru

Status: Offline
Posts: 652
Date:

The only fuel you can buy now without some amount of Ethanol blending is Shell Premium.

__________________

72 Nova SS - Minitubbed
70 Nova SS - #'s L-78 Bench Stick
68 Acadian SS clone - factory air
67 Chevelle rag - SS 427 clone



A Poncho Legend!

Status: Offline
Posts: 20744
Date:

My gas never goes bad in under a year. I get 20 litres of high octane gas, then add octane boost, Stabil, lead additive, and gasline antifreeze. I shake it ... never stirred!biggrin



__________________

Prince Edward Island

'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.

Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.

Tweet this page Post to Digg Post to Del.icio.us
.
Support Canadian Poncho!
Select Amount:
<
.
.
.