Car Stalls Going Downhill

[cstew47]

I have a K5 Blazer with a 383 stroker. The carb is an Edelbrock 1405, 600cfm. It has begun stalling when I go down a fairly steep hill. I have checked the floats and they seem to be correct. Is this a fuel pressure problem? Has anybody else had this problem?

 

[oldretiredafguy]

I have a K5 Blazer with a 383 stroker. The carb is an Edelbrock 1405, 600cfm. It has begun stalling when I go down a fairly steep hill. I have checked the floats and they seem to be correct. Is this a fuel pressure problem? Has anybody else had this problem?

Single tank or dual? Fuel quantity when this occurs? See where I'm headed with the questions?

 

[AuroraGirl]

Have you tried going uphill


Joking, but seriously does it do it uphill too

 

[cstew47]

No, it seems to only do it when I am descending. I've tried to find just uphill routes.

 

[cstew47]

It is a single 25 gal tank. The tank has been full. I just put a new sender in.

 

[cstew47]

test

 

[Paladin]

FWIW I had a similar problem once except my truck tried to stall and die only when going up an incline, and it didn't have to be much of an incline either. Turned out the fuel pump was in the process of giving up the ghost! New fuel pump immediately solved the problem!! BTW Welcome to the forum. Now I can claim to have a Columbian connection!!! LOL

 

[Rusty Nail]

No, it seems to only do it when I am descending. I've tried to find just uphill routes.

Back in the day they used to have them ways to school or work or church that were uphill both ways, wonder what ever happened to that? Maybe it had to be snowing?

It is a single 25 gal tank. The tank has been full. I just put a new sender in.

Bingo!
Ah-ha..?

It's quite obvious from here that you are pulling the electrical connection loose on incline. I recommend going back over these exterior connections at the tank and finding some slack.

(And take pics this time. Good Grief!)

You must be registered for see images attach

 

[AuroraGirl]

Remember uphill means that fluid is now being pulled up that distance snd elevation not just distance before it can then be pushed up a few feet to the carb

for whatever reason, you’re most likely running into a fuel demand keep up problem or a blockage that makes itself obvious at that angle. Did you make sure lines are clear when you changed sender maybe you have something blocking the line or pickup in a way that it can deliver enough most of the time

also it just took me to now to remember you said downhill.
Um. The last part I just said is still possible, don’t discount the blockage to check. Are you in a auto trans in gear/neutral or you in a manual in neutral/engine braking
Also consider your fuel hose, is it routed properly when you reinstalled your tank and sender.
? Does it perhaps push up into a kink or pin itself when the weight of the tank etc are pushing forward ?

if you are still using a manual linkage on your choke, does the choke only move when you use the knob/is the choke closing on downhill from some mechanical improper something
An engine with very little load but some rpms amd rich AF mixture and high vacuum not adjusting your advance etc you see where I’m going

Because of your directionality I would just be seriously looking at physical obstruction or blockages in fuel system

I would also consider fuel pump age or fuel pressure if you have a good volume pump, poor internal seals , high flow filter, maybe yku have gas applying more pressure on itself and that is overcoming your carbs float or whatever gas likes to go past on edelbrocks.
You didn’t mention fuel pressure regulator and I don’t have one either but I’m only off road atm I don’t have any cruising to test drive ability yet. I’m sure if I was all squared away a regulator would be needed

 

[cstew47]

I suspect the reason that it doesn't stall going uphill is that I am running rpms. Going down I am idling. If I keep the revs up going downhill it will keep running. That tends to push me towards the fuel pressure conjecture. I haven't had a chance to put a gauge on it yet, but, I will. If I'm getting less than 4.5 psi, I suspect that the fuel pump isn't keeping up.

 

[Backfoot100]

Sounds like the float is too high to me if it stays running by adding throttle. On the downhill grade you're getting fuel spilling into the carb throat and basically flooding the engine. Keeping on the throttle is keeping the RPM high enough to burn the spilling fuel without flooding.

You'll need some assistance to do this. Take the air cleaner off and get it running.
Get the truck on a downhill incline to simulate the problem. Have someone in the driver seat to hold the brake or keep it running. You can crawl up by the carb and look down the throat. If gas is pouring down the throat the floats are too high.

Same issue can happen with boat engines that are angled down a lot more than auto engines.
Setting the floats by the book will keep flooding the engines.

 

[kenny78]

It’s been a while since I moved off of edelbrocks, but on my blazer it would stumble and go erratic if I hopped a curb or off kilter at all. Fuel pressure had to be tightly controlled from pushing past the seat, float level kept perfect and I even put the off road seat in.

I know yours is on the street but thought I would share.

 

[Raider L]

I can't imagine where a overflow situation in the carb by just going downhill. Like, what angle are we talking about? 20 deg., 40 deg.? Man, that's quite an incline that would cause spillage inside the carb. I don't get it. I've not had a problem, nor even heard of this situation before. I've had a blockage in my fuel line before that only happened when I accelerated on level ground. It turned out to be a little piece of something in the line, and when I gave it gas the engine would die. But if I was driving real slow it was okay.

I found the problem by taking the line off the carb., starting the engine, standing next to the car and reaching over to the carb., gave it gas and this little black piece of something came out of the fuel line into my hand. I hooked everything up and the stall never happened again. I don't know how that piece got past the filter.

This could be similar in that something is rolling down to the carb only on an incline. Take the fuel line off the carb., start the engine and see if anything comes out of the fuel line. Now, don't catch yourself on fire, or burn the truck up either! Rig it so you catch all that gas. When I was standing there next to my car with the fuel line off that time, I bent the metal fuel line over away from the engine and the fuel was going onto the ground. Oh yeah, I was pulled off to the side of the street in traffic to.

 

[RecklessWOT]

Does it idle normally sitting still? Does it stall if you coast for a long period of time on flat ground? Get it going fast then take your foot off and coast and see if it does the same thing. If it does stall just because you're not giving it gas I would start looking for vacuum leaks

 

[bedwards]

Crap rolling around in fuel bowl over the jets?