Engine stalls when accelerator is pressed.
Thread Starter
|
Tuned
Joined: Feb 2016
Posts: 299
Likes: 0
Engine stalls when accelerator is pressed.
I feel like I am back to square one. 1979 f150 400 6.6 liter. I installed new Holley 600, new distributor, new fuel pump, new intake manifold gasket and new valve cover gaskets. Changed oil and filter. I started engine and let idle for 5 minutes no smoking engine. An hour later I restarted engine pulled forward approximately 20 feet to hose driveway off. Truck idled approximately 10 minutes, no problem. I put it in drive press accelerator and it dies. I restart and back up to original starting point, press accelerator and it dies. Restart it and let idle. This time black smoke is coming from exhaust pipes. The number 5 exhaust rocker arm was slightly loose and bolt was bottomed out when I replaced everything. Engine is not running hot. Oil pressure gauge moves to normal and then goes back to L. It is also brand new 2 months ago. Thanks for any advise.
Thread Starter
|
Tuned
Joined: Feb 2016
Posts: 299
Likes: 0
Okay. I'll check that. Didn't think about being out of time since we set timing at top dead center on number 1 cylinder. I don't know where a vacuum leak would be. I did see if havery a small gas leak at the filler neck clamp.
Cargo Master
Joined: Jun 2014
Posts: 2,212
Likes: 322
From: Central Florida
On the harmonic balancer, TDC will come up twice for every full rev of the cam, once for #1 and once for its opposite in the firing order. Thus, you need to confirm that you have the correct TDC (TDC firing) when you install the distributor. Otherwise, you might be 180º off. When you're at TDC (firing) for cylinder #1, both valves will be closed and the piston will be at the top.
Once you are certain about that, set the initial advance and check to see if the rotor is pointing to the wire for #1 by peeking under the dist cap. It's easy to be off by a tooth or so on the dist gear. While you're there confirm that your spark plug wires are following the firing order in the correct (CC) direction, not cross-firing, grounding, etc.
A Q&D way to find TDC (firing) is to wad up a piece of paper large enough to cover #1 spark plug hole. Then "bump" the starter until the wad pops out. That's TDC firing. This will require a confederate or a remote starter button.
Once you are certain about that, set the initial advance and check to see if the rotor is pointing to the wire for #1 by peeking under the dist cap. It's easy to be off by a tooth or so on the dist gear. While you're there confirm that your spark plug wires are following the firing order in the correct (CC) direction, not cross-firing, grounding, etc.
A Q&D way to find TDC (firing) is to wad up a piece of paper large enough to cover #1 spark plug hole. Then "bump" the starter until the wad pops out. That's TDC firing. This will require a confederate or a remote starter button.
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Black smoke = too rich a mixture - letting un-burned hydrocabons out the exhaust. The mixture screws should be about 1- 1.5 turns out.
Check yer plugs- I'll bet they're black/sooty - and clean/replace.
How's yer accelerator pump? With the engine off and semi cool, blip the throttle - you should see two lines of fuel shooting down the carb body.
Trending Topics
Postmaster
Joined: Nov 2015
Posts: 2,769
Likes: 7
From: O-O-O-Oreilly's
You mechanic set it to full manifold vacuum..which means you have full vacuum advance all the time. Waay too much initial. It can be a good thing but needs other considerations to run right. Pull the line and plug the bottom nipple. Plug the line and recheck yer timing. Should be ~ 12*BTDC.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Thread Starter
|
Tuned
Joined: Feb 2016
Posts: 299
Likes: 0
Okay I'll take care of vacuum advance. The truck idled perfect for 20 minutes, then started to bogg down like it was going to die. The ran smooth for a couple of minutes then eventually died. I'll check spark plugs, but I just put them in 2 months ago. There's not 10 miles on them.
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
No, vacuum advance is load related while mechanical advance is RPM related.
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Bogging down at idle, then dies.....black smoke out the exhaust, probably fouled plugs...
OP: for grins and chuckles, check the power valve. To do this, bottom out a mixture screw - go easy! If the engine still runs, the power valve is shot...if it dies, the power valve is good and some other troubleshooting is necessary.
I know you said the carb is "new" but stranger things have happened "out of the box."