Truck backfiring at full throttle

[patd]

A couple of days ago while driving home along the freeway the truck started to hesitate and back fire while going up a long uphill grade, It happened at exactly the same place a week before. It is the only place that I drive it with the throttle to the floor to try and keep up with the traffic, it starts to loose power and hesitates, and back fires if I pump the throttle. I am thinking it might be the ignition that is why I want to go with the electronic ignition, anybody have any ideas what it might be? :hmm:

[MicroMachinery]

Your timing might have slipped. I JUST got done dealing with that.. my timing had gradually been retarding over time, then I went on a long drive that pushed it over the edge. I cleaned my points, lubed my vacuum advance, and advanced my timing back to where it wanted to be. Runs amazing now.

If I were you, I'd start by checking the base timing, and make sure that the vacuum advance is moving smoothly. What do the plugs look like? When's the last time you looked at your points?

[patd]

Thanks for answering, I just put new plugs in it that same morning, It ran fine all day until I was heading home, I only drive it around 60 mph on the freeway, and never at full throttle until going up that grade, I just drove it and it back fires and hesitates when I floor it while accelerating. I took a look at the points today and one of them has a small pit on it, I will have to get a timing light to check the timing, The manual that I got with the truck is half missing and just as luck would have it the last page is Chapter 4 Ignition system, at least it has the points/plug gaps on the page. I am really wanting to put an electronic ignition on it to get rid of these problems.

[hang_510]

I am really wanting to put an electronic ignition on it to get rid of these problems.

i should have one avail next week.

 

wont prevent setting the timing correctly!

 

 

trade for??? something in the back cases? ;)

[patd]

i should have one avail next week.

 

wont prevent setting the timing correctly!

 

 

trade for??? something in the back cases? ;)

 

I have some new parts that I have not used, Clutch, Clutch housing, 4 new brake hubs, oil pump if not let me know how much you want. :hyper:

[racerx]

That happened to my 510 awhile back and not sure if it was the coil or the rotor. But check them out, may want to check your wires and distributor cap, maybe corrosion

[datzenmike]

A couple of days ago while driving home along the freeway the truck started to hesitate and back fire while going up a long uphill grade, It happened at exactly the same place a week before. It is the only place that I drive it with the throttle to the floor to try and keep up with the traffic, it starts to loose power and hesitates, and back fires if I pump the throttle. :hmm:

 

Change the fuel filter first.

 

If you haven't changed it in the last year or so, do it. You've nothing to loose, they're only $5-$7. Sounds like you may be running out of fuel on those long up hill climbs.

[patd]

Change the fuel filter first.

 

If you haven't changed it in the last year or so, do it. You've nothing to loose, they're only $5-$7. Sounds like you may be running out of fuel on those long up hill climbs.

I have a new one in my parts box, I didn't install it as the one on it when I bought it looked pretty new, but I have no idea how long it has been on there. I did not get any history on the truck when I bought it, All I know that it was last registered back in 94, and was most likely sitting in a shed or garage since then. I will give it a try. Thanks.

[datzenmike]

Looks are only skin deep didn't mom tell you that? :lol: If you don't know the history, replace it. This goes for tranny and rear end oil, rad coolant, engine oil and filter. When you have time that is.

[patd]

Looks are only skin deep didn't mom tell you that? :lol: If you don't know the history, replace it. This goes for tranny and rear end oil, rad coolant, engine oil and filter. When you have time that is.

Yeah she told me that but I didn't listen to her, lol That is one thing that I did do, Replace all of the fluids in the truck, Engine,transmission, rear end, and radiator, new oil and air filter, new plugs, distributor cap and wires, drained the gas tank, but I should have replaced the fuel filter, I don't know why I didn't. I have a new one in my parts box. The truck was donated to some charity and a dealer was selling it on ebay, it looked like someone tried to get it started at some time and replaced the points and condenser as they looked new. and rebuilt the carburetor. I bought the parts before the truck was delivered and I got the wrong points,(single)so I just left the ones that came with it in, So I don't know how old the points really are. I used to have a 73 240Z that I bought back in 79, This has brought back memories of that car as I used to change or clean the points about every six months. I should have kept that car, it was a blast driving it. oh well live and learn.

[banzai510(hainz)]

I would time it to about 10deg BTDC and also remove the 2nd set of points wire and run it on that hill and see what happens.

[patd]

Change the fuel filter first.

 

If you haven't changed it in the last year or so, do it. You've nothing to loose, they're only $5-$7. Sounds like you may be running out of fuel on those long up hill climbs.

 

OK I really don't want to say this, But if it helps someone else in the future its worth it, I just went out and took the old fuel filter off and a bunch of brown/red fluid crap came out of the bottom connection, I shook it around and more came out, also a fine powder/dirt. I put on the new filter on and let the truck warm up and took it for a spin, As of right now she is running just fine, I floored it as I went through the gears and no back fire or hesitation at all, I adjusted the points yesterday and went for a drive and it was hesitating and backfiring under acceleration. She would run ok at a steady rpm but not at full throttle, So to give it the ultimate test I am going to take her on the highway to that grade and see what happens. I am still going to get the Matchbox EI Ignition, but at least now I can driver here again. I will let everybody know how the test drive goes. :wacko:

[banzai510(hainz)]

521 the fuel fller hose is in the wheelwell?also very fine dirt can work its way in there. what happens water can run inside the filler tube and rust out the tank which can clogg up the idle jet and or jets. Happen many times on my 521 being washington has alot of rain.

 

I told you to rmove the wire to the second set of points. This will eleiminate if there are dwell of 3rd gear swtich proplems. Be honest I dont know if 521s have the switch or not. 510s do for sure.

 

also ck the dizzy shft for excess play/bushing wearing out. could cause points to open up prematurely

[521newbie]

521 the fuel fller hose is in the wheelwell?also very fine dirt can work its way in there. what happens water can run inside the filler tube and rust out the tank which can clogg up the idle jet and or jets. Happen many times on my 521 being washington has alot of rain.

 

I told you to rmove the wire to the second set of points. This will eleiminate if there are dwell of 3rd gear swtich proplems. Be honest I dont know if 521s have the switch or not. 510s do for sure.

 

also ck the dizzy shft for excess play/bushing wearing out. could cause points to open up prematurely

 

Can you elaborate on the third gear switch? Where is it and what role does it play? It sounds like it may be what's wrong with my truck.

[banzai510(hainz)]

have to look at a 521 diagram. as I dont know if there is one on a 521 as I converted mine to single point then to a Pertronix unit. I assume since it has dual points there will be a relay somewhere for it.

On 510 its near the radiator on the driver side and there is a swithc by the firewall with a clear plastic cover(most of these get pulled out and thrown away.for troube shooting just pull the 2nd set points wire and see if it diassapears

[patd]

Well I took her for a ride to check her out after changing the fuel filter and she ran better than she ever has. Not only did I make it up the grade but she actually accelerated up to 70 with no problem. Damn one little filter can cause so much grief. Thanks everybody for all of the help that you gave me.! :thumbup:

 

Went to my favorite place in the whole wide world

 

Stopped on the way back to get something to eat. This place has the best hamburgers in the world

 

I told you so..

 

The Grade

 

The fuel filter, It was worse than this when I removed it

[HRH]

You might want to get a spare fuel pump to carry with you just in case. Hopefully the filter did it's job, but in case some got through.

[patd]

i should have one avail next week.

 

wont prevent setting the timing correctly!

 

 

trade for??? something in the back cases? ;)

 

When you get one available, let me know how much you want for it, Do you have a paypal acct?

[Roadracer Al]

If your fuel filter is that full of rust, you probably would benefit from dropping the gas tank and cleaning it out real good. Radiator shops will hot dip the tank and repaint it for a modest fee.

[patd]

If your fuel filter is that full of rust, you probably would benefit from dropping the gas tank and cleaning it out real good. Radiator shops will hot dip the tank and repaint it for a modest fee.

 

That is a good idea, I drained it when I first got it, but I am sure there is a lot of sediment inside it. I think I will look into it today.

Thanks for the tip :thumbup: