Any Chevy guys here who can help me?

Nick_the_'Nole

Super Member
I just got myself a new toy, but it's giving me all sorts of headaches trying to get it running. It's a 1985 Caprice Classic with the 305 and a Quadrajet. It turns over, and with gas poured directly into the carb it'll crank up for a couple seconds, but it just won't continue getting fuel. The fuel tank was bone dry while it was sitting, so I doubt it's gas separation or condensation, and I can hear some sort of noise from the fuel pump when I click it on, but at the same time it doesn't seem like just a simple fuel filter problem since there's no fuel getting to the carb at all. Anybody have ideas about the most likely culprits? I'm a Ford guy, so I'm in kinda foreign territory here.

Also with the fuel filter, I'm not so sure about that setup on the carburetor, seems a little trouble-prone to me. Is it safe to take out that little stone thingy and just put a glass filter a little farther back in the line?

I'm also trying to track down a source for some 9C1 police springs for this thing. It's got the rear-end sag going, so I figure if I'm gonna put effort into fixing that I may as well upgrade it too. Does anybody know where to get those or equivalents? None of the local junkyards have anything of the sort.

I'll try to get some pictures of this beast once I get it cleaned up a bit... Even with the problems it has I think it was a really good deal at $500. It does run, once I get fuel going to it, and only has 80k miles on it. Some suspension work and a new coat of paint should have it nice again without too much trouble.
 
That stone thingy is indeed the fuel filter. An electric fuel pump usually has higher pressure than a mechanical one, so the pressure may blow the bowl of a glass one.

No fuel at the carb usually would mean pump replacement. Check for kinked or rusted-out fuel lines nevertheless. My family owned plenty of GM iron over the past 50+ years, so I have a very little bit of knowledge here.

For springs, if you can't get genuine police ones, ask around for springs for trailer towing. Much stiffer, and they work. :yes:

Tom
 
Last edited:
If it's an 85 and has a carb, it'll have a mechanical pump on the engine, not an electric one in the tank.

If the tank now has some gas in it, you may have to crank for some time while pumping the foot feed.

This will "purge" the fuel line so it has fuel up to the carb.

Check where the fuel line from the carb runs to... if it is a mechanical pump, it will mounted on the side of
the engine towards the front.

It may be bad and not pumping any fuel.

Hope this helps...

Scott
 
Hopefully, TA will see this. He has a primo Caprice Classic. Think his is an '87. I don't recall if there is a fuel pump in the tank on this model, or not. Some models had them there and they are a pita to get to and work on. Buy the Chilton's manual. You can probably find on on eBay. If not, then get one from Amazon. IIRC, some of the Quadrajets had a screen on the inlet to the carb, as well. If generally comes out when you remove the gas line at that carb. That could be blocked. Take the line out and then turn on the key and see if you get any fuel to flow through the link. It may be that you need to back-fill the line with gas to prime the pump, which could be vapor locked. I doubt it, but couldn't hurt.

I agree with your analysis. Excellent automobile. I pine for my '92 Roadmaster all the time. Best car I've ever owned. May just have to get another. Can buy a lot of gas for the $15K difference between it and the Vibe I'm looking at.

OvenMaster said:
How did you manage to get an '85 with a Quadra-Jet?Tom
No FI on a 305 until '90, IIRC. My '84 Oldsmobile and '88 Fleetwood Brougham both had a QuadraJet. When I traded the '88 for a '95 STS it was an amazing difference. The STS was about 10-times as fast, handled like a sports car and got 9mpg better mileage. Wasn't quite as comfortable, though.
 
Last edited:
OvenMaster said:
Last I recall, 305's started having some sort of FI in 1981.

A lot of 85s still had the carb on 305s (My 85 Silverado with a 305 had a Q-Jet on it).

Scott
 
disconnect the fuel line at the carb, crank the engine and check for fuel pressure.
 
OvenMaster said:
How did you manage to get an '85 with a Quadra-Jet? That should have some sort of throttle body FI on it. :dunno: If there's a carb, it may not be an '85 engine. Last I recall, 305's started having some sort of FI in 1981.


Tom

I'm not positive but I belive that 350's got TBI in '81 however 305's did not until '86
 
Well, it's definitely a Quadrajet, and as far as I can tell and as the original owner knew it's original to the car. Don't ask me to try and explain it, but that's what's there.

So I should just keep the stone thing in there, then?
 
Hang in here with me Nick, it's only been about 20 years since the last time I fooled with a Quadrajet - Here goes...

I think step one would be to replace the fuel filter(s) then check the carb-inlet pressure off the fuel pump, a Chilton's or Hayne's book will give you the correct range (my local library has a bookcase devoted to them, and it'd save having to buy one if yours does too). It shouldn't have to be too high, 40 psi mebbe?, but if it's only pumping at 15 or 20 psi, it may be that the pressure is just so low it won't fill the float bowl. Your local auto supply should have the gauge set-up to do it. If it turns out that the pressure is too low, it's an easy replacement.

If your fuel pump is still good, it's almost for certain that your Q-jet is in need of a rebuild. The good news is the kits are cheap (relatively), the bad news is that Q-jets are a pain in the butt to rebuild, at least compared to simple carbs like Holley's. they have a ton of tiny inlets, and fiddly parts that seem to bounce a country mile when you drop them.

If it were me, and the carb turns out to be the problem, I'd find a vacuum secondary Holley 600 or even a 650, and an square-bore/spread-bore adapter plate. I had a similar situation on an Impala (327) years ago, and I got so tired of fooling with the Quadrajet I replaced with the above suggested parts. Never had to touch the carb again.

Keep in mind that I'm just suggesting this as an alternative to a tricky rebuild, you may not want to sink that much money into it - If you're a really patient feller, you might actually enjoy working on that Quadrajet. Of course you'll know best when you start tearing into it... BTW - Nothing moans like a Q-jet when the secondaries kick in, very cool!

Good luck buddy, hope it turns out to be real simple!
 
As others have said, it should have a mechanical pump. Chev kept the q-jet well into the 80's, prehaps longer.

I wouldn't cut the fuel line. Glass will open up in a fire as will plastic. Having rubber fuel lines under pressure dramatically increases the chances of a fire, too. Especally if the metal lines havent been bulged at the ends so the hoses cannot slide off...

I used to really hate to see those come in cut, because it makes the carb fitting such a pain to deal with.

Get a wrench that actually fits the big nut, and a real tubing wrench that fits the flare. You have to hold the big nut while you crack the flare. With tools that fit, these stock filters are no problem and really work well.

I suspect if you have a stone thingy it is probably wrong for the year. I think it should be a paper cartridge. The hole in the paper cartridge goes toward the fuel line in the big nut. there are two lengths of paper cartridge. If it takes the short one, there will just not be room for the long one. The spring goes between the paper cartridge and the carb body. There is a white plastic gasket that snaps around a lip on the end of the big nut. The gasket has to be there. All this assumes that is really is a mid-80's setup. If it's a lot older the details could be different.

This is an extremely reliable setup, and only seems to get screwed up when (a) someone tries to crack the flare nut without holding the big nut or (b) cross threads the fine threads on the big nut. Start it by hand.

If it plugs, it just blows off and bypasses. Thats what the spring is for. This shouldnt cause a no gas condition no maatter what (unless someone assembled it wrong).

Good Luck :)

John
 
piece-it pete said:
I'd say the guys got the fuel covered - for springs I'd call Summit Auto Racing:

http://www.summitracing.com/

Fair prices, great service, huge inventory. Good luck with your now-classic Cruiser!

Pete
I'll second these guys I've been using them on a race car and a couple street cars for years, fast shipping also.
 
I'd double check the specs before expecting 40psi from the stock fuel pump with a Q-jet. We just put a regulator on my son's El Camino that came stock with a Q-jet because the pressure from the new pump was about 12psi at an idle, between 7 & 8 pounds higher that recommended.

Larry
 
bentpencil said:
I'd double check the specs before expecting 40psi from the stock fuel pump with a Q-jet. We just put a regulator on my son's El Camino that came stock with a Q-jet because the pressure from the new pump was about 12psi at an idle, between 7 & 8 pounds higher that recommended. Larry
Absolutely. The only thing holding back the pressure from the pump is the float valve. It is designed to handle about 4-8 pounds. Anything higher will lead to flooding and a very rough idle and low-speed operation. This isn't an FI system that needs the pressure to atomize the gas being sprayed into the TB throat or the individual injectors with SPFI. And, those systems have a return rail and over pressure valve to route the gas back to the tank in many cases. Carbs run on very low pressure and rely considerably on the vacuum created within the intake manifold and piston on the downstroke to get a combustible charge into the engine.
 
fotno said:
then check the carb-inlet pressure off the fuel pump,

It shouldn't have to be too high, 40 psi mebbe?, but if it's only pumping at 15 or 20 psi, it may be that the pressure is just so low it won't fill the float bowl. If it turns out that the pressure is too low, it's an easy replacement.

Fotno, Nick's car should have the mechanical fuel pump, so 40 PSI from that pump would be unlikely...

A Q-Jet only needs about 6-7 PSI to run right.

I still believe that if the mechanical pump is okay, then it might just need to crank for a while to bring
the fresh gas up from the tank.

If it doesn't start after about 10 to 15 tries, then I'd look into the fuel pump.

Scott
 
And, to speed things up and save wear and tear on the starter, you might pull the spark plugs out first, so the engine can spin under no load.
 
Hey, if you are going to change springs I just noiticed that I have a set of spring compressors in the garage. Now the thought that I am likely to crawl under a car and change springs is to laugh. If you want them they are your for the shipping.

Rob
 
I would just replace the fuel pump out of hand as a start...it is inexpensive (less than $20.00) easy to replace and that takes that out of the picture as a potential problem in the future. If some starting fluid is sprayed into the carb, the engine then started up with some fuel in the tank, you should get enough fuel from the starting fluid to run the engine long enough to fill up the float bowls.
 
DO NOT put a glass fuel filter in line. That is an underhood fire waiting to happen. The metal can AC fuel filters for mechanical fuel-pump supplied carbs are excellent. If I installed on with rubber hose, I would make sure the stock metal lines are flared to hold the rubber. The non-electronic Q-jets are great carbs and can be tweeked, too. I'm biased though, I edited "Rochester Carburetors" by Doug Roe, HPBooks back in the '80s.
 
Last edited:
Back
Top Bottom