Dies on speed bumps/sudden spots

[mistaake]

Dies on speed bumps/sudden stops

OK... this is a wierd one...

Literally 5 mins after buying the truck I was driving to my friends place to pick him up so he could drive my other car home. Anyway, his apartment complex has some nasty speed bumps. I take them too fast... the burb would die each time I went over one not-super-slow.

At the time our theory was that it was low on fuel and the speed bumps sloshed the fuel around enough to the point it would get starved on fuel. Since it restarted after lots of pumping gas pedal and cranking each time, and drove the 1 block to gas station (no major pumps or sudden stops) fine, and ever since it's been fine. That day I got like 13gal gas if I remember right, and the other day I got maybe 8gal? I have no idea if fuel gauge works, and it's a pain to fuel because the hole is not angled like newer cars... which is why I never filled it up all the way - I'm not a patient person.

Anyway, it's been fine for like a week. Until today... was driving home, and had to stop really suddenly from I would guess 35mph. The transmission seemed to downshift really, really hard, and the engine died... I was able to roll to the side of the road.

It required a lot of cranking to get the engine going again. Like, enough cranking I was afraid the batteries couldn't handle it. But, got it going, and went to nearest gas station. Got like 20 gallons. I don't know if it's actually full (again, no clue if fuel gauge is accurate) but it seems like it was since it would not accept more gas. Either way, I can't image it was out of gas, since it's a 40 gallon tank?

So, what could the problem be? I don't want the truck to die on me at an intersection, in the middle of the road, or on the highway. I just really don't know to check since it runs fine otherwise. I'm thinking fuel filter maybe? Input appreciated!

 

[Jarhead79]

Fuel sending unit? Fuel pump? Bad ground, battery terminal loose?

 

[mistaake]

Fuel sending unit? Fuel pump? Bad ground, battery terminal loose?

Alright... so I need to check all grounds and maybe clean them. Since I'm having other electrical issues (occasional no crank no start and low voltage) this makes sense. Do you know if there is a diagram so I can do this?

Fuel pumps are cheap, so I wouldn't mind replacing it, but I personally don't see how it could fail, since it's mechanical - then again I'm pretty clueless about these things. Fuel sender is expensive and seems like a pain to do, so further testing might be a good idea before I do that.

Maybe I should try replacing the issue on a side street and spray starting fluid in when it doesn't want to restart to see if it's a fuel issue?

And I'm still a bit worried about the hard downshift that came right before the engine died. Or is that issue just because the engine stopped running while the truck was moving and in gear? The hard shift seemed to come right before the stall but I am not 100% sure about that.

 

[Jarhead79]

Something else to check, my truck died on me I out of the blue and wouldn't turn over, it was just a simple issue with the wire that went into the distributor cap, I had messed with some wires just prior to driving it, it lost good connection and died, would crank but not start, I pushed in the wire and then it fired. Worth a check.

 

[CRM]

Dying over speed bumps sounds like there's not enough fuel in the carb reservoir, indicating a partially plugged filter or maybe the float needs adjustment. Jarhead's wiring suggestion is good too.

 

[RetroC10Sport]

Mechanical pumps do wear out.

We do have wiring diagrams for download in the library. http://www.gmsquarebody.com/forum/showthread.php?t=14498

 

[mistaake]

Mechanical pumps do wear out.

We do have wiring diagrams for download in the library. http://www.gmsquarebody.com/forum/showthread.php?t=14498

Could the mechanical fuel pump wearing out cause the issue I am describing?

And I downloaded wiring diagram but holy cow... that's a lot of wiring!

 

[RetroC10Sport]

Possibly but not likely. A worn fuel pump would cause it to quit running or run poorly. I was just stating that they can wear out.

And yeah, the schematics are intimidating, but once you understand them a little, they are actually really easy to follow. Try readying the schematics from a NEW truck!

 

[mistaake]

Possibly but not likely. A worn fuel pump would cause it to quit running or run poorly. I was just stating that they can wear out.

And yeah, the schematics are intimidating, but once you understand them a little, they are actually really easy to follow. Try readying the schematics from a NEW truck!

ok, gotcha, thanks. and yeah, why do you think i bought such and old truck... was trying to avoid electrical bs... lol

 

[theblindchicken]

Had an issue once at school where the speed bumps were ridiculous. Tall and super short in length. Hit it a little too quick. Ended up getting the carb float stuck. killed the engine, and wouldn't restart til it got loosened.

Sent from my SM-G935P using Tapatalk

 

[Quadrajet Power]

I was also going to say possible carb float issue. Or fuel supply to carb somehow. Are you running the quadrajet?

 

[mistaake]

Yeah, I'm running the stock carburetor.

 

[bucket]

Agreed, sounds like a float issue.

When you put the 20 gallons in, what did the gauge say before and after? And do you folks have different gas pump nozzles out there? When I was driving my '77 K5 everyday, I never had any trouble filling it up.

 

[mistaake]

Agreed, sounds like a float issue.

When you put the 20 gallons in, what did the gauge say before and after? And do you folks have different gas pump nozzles out there? When I was driving my '77 K5 everyday, I never had any trouble filling it up.

So, I should take it to the shop to check and adjust the float? I don't understand carburetors.

 

[highdesertrange]

I was going to ask what carb it had. Quadrajets really aren't known for this issue but It could happen. the old carter carbs were well known to have this problem the solution was to install off road needle and seats. your problem sounds just like this problem you hit a bump and a ton of gas sloshes down the carb killing the engine. then the reason you need to crank it allot is because the engine is flooded. highdesertranger