sdsurf Posted December 31, 2009 Report Share Posted December 31, 2009 I having some fuel delivery issues. Looks like I either have a spordic clog in the lines or something is going on with the fuel pump. What happens is I will get the float filled in the carb and it will run for a while just fine then all of a sudden it won't get fuel. I disconnected the fuel filter and ran without it and it seemed fine. Put in a new filter and again it seemed fine and then the same thing happened, it went dry. before you ask, 1/2 tank of gas... Quote Link to comment
Skib Posted December 31, 2009 Report Share Posted December 31, 2009 I having some fuel delivery issues. Looks like I either have a spordic clog in the lines or something is going on with the fuel pump. What happens is I will get the float filled in the carb and it will run for a while just fine then all of a sudden it won't get fuel. I disconnected the fuel filter and ran without it and it seemed fine. Put in a new filter and again it seemed fine and then the same thing happened, it went dry. before you ask, 1/2 tank of gas... this is with the 521 Im assuming? Quote Link to comment
sdsurf Posted December 31, 2009 Author Report Share Posted December 31, 2009 this is with the 521 Im assuming? correct Quote Link to comment
Skib Posted December 31, 2009 Report Share Posted December 31, 2009 correct is there anything in the filter? anything in the lines? Quote Link to comment
banzai510(hainz) Posted December 31, 2009 Report Share Posted December 31, 2009 [quote name='Skib' date='31 December 2009 - 06:09 AM' timestamp='1262268595' po I had a stock Hitachi with the sight glass ans I could see it was full then run out of gas. I would wack the carb near the needle valve then gas would go in. Quote Link to comment
Skib Posted December 31, 2009 Report Share Posted December 31, 2009 I had a stock Hitachi with the sight glass ans I could see it was full then run out of gas. I would wack the carb near the needle valve then gas would go in. A bent needle on that one Im assuming? (Iv just worked with SU's) another Q for the list tho, what carb are you running? when it stops flowing are you getting fuel in the lines after the filter? how about the lines before the filter? Quote Link to comment
RoadRace Posted December 31, 2009 Report Share Posted December 31, 2009 I having some fuel delivery issues. Looks like I either have a spordic clog in the lines or something is going on with the fuel pump. What happens is I will get the float filled in the carb and it will run for a while just fine then all of a sudden it won't get fuel. I disconnected the fuel filter and ran without it and it seemed fine. Put in a new filter and again it seemed fine and then the same thing happened, it went dry. before you ask, 1/2 tank of gas... i can't see what i'm typing so bear with me! nice looking forum...but the text option header bar is directly over the text field. very odd i have had a problem similar to this and it was water in the fuel clogging the filter. with ethanol blended fuels its more of a problem. also make sure the pump is not damaged or leaking. make sure the carb is venting properly and the rest of the fuel system for that matter. Quote Link to comment
sdsurf Posted December 31, 2009 Author Report Share Posted December 31, 2009 is there anything in the filter? anything in the lines? It is a brand new filter and I ran it with and without. I have blown out the lines numerous times. A bent needle on that one Im assuming? (Iv just worked with SU's) another Q for the list tho, what carb are you running? when it stops flowing are you getting fuel in the lines after the filter? how about the lines before the filter? Hitachi carb. Also I filled up the float and fired it up with the fuel disconnected and did not get gas when the engine was running (fuel pump pumping). i can't see what i'm typing so bear with me! nice looking forum...but the text option header bar is directly over the text field. very odd i have had a problem similar to this and it was water in the fuel clogging the filter. with ethanol blended fuels its more of a problem. also make sure the pump is not damaged or leaking. make sure the carb is venting properly and the rest of the fuel system for that matter. I haven't heard of venting the carb. How is this acheived? Is there a valve somewhere I may be missing? Quote Link to comment
Skib Posted December 31, 2009 Report Share Posted December 31, 2009 do you have a return line? Quote Link to comment
DanielC Posted December 31, 2009 Report Share Posted December 31, 2009 Disconnect the fuel line at the fuel filter, that goes to the gas tank. Blow air back to the gas tank, and see if there is some kind of clog at the fuel pick up in the tank. If there is, this works as a temporary fix, but you need to clean out the tank, probably by dropping it, and dumping any crud out, and rinsing it out. Quote Link to comment
sdsurf Posted December 31, 2009 Author Report Share Posted December 31, 2009 do you have a return line? Off the carb? if so where would it be? I also noticed in the glove box manual it says "two" fuwl strainers. Am I missing one other than under hood? Quote Link to comment
banzai510(hainz) Posted December 31, 2009 Report Share Posted December 31, 2009 Off the carb? if so where would it be? I also noticed in the glove box manual it says "two" fuwl strainers. Am I missing one other than under hood? 521s dont have a return line. Once it runs out of gas. pull th fuel line to carb. then crank and see if gas shoots out line. if yes then I assume its the carb I cant read what Im typeing on this. then on the right side it dissappears under the scroll bar admin please fix Quote Link to comment
DanielC Posted December 31, 2009 Report Share Posted December 31, 2009 The late 1971 PL 521 pickups with an evaporative emission system did have a fuel return line. Most 521 pickups did not. Quote Link to comment
sdsurf Posted January 2, 2010 Author Report Share Posted January 2, 2010 What is the best idle adjustment on a Hitachi? Or How do I do it? Quote Link to comment
DanielC Posted January 2, 2010 Report Share Posted January 2, 2010 Set timing first, 10 degrees before TDC. Check valve clearance adjustment. .008, intake, cold, .010 Exhaust cold. .010 Intake hot, .012 exhaust, hot. Warm the engine up completely. Adjust the idle speed and mixtures screws for the best idle, at 750 RPM. Then adjust the mixture screw in to drop the idle speed to 700 RPM. You can use a vacuum gauge to find the best idle mixture. Quote Link to comment
datzenmike Posted January 2, 2010 Report Share Posted January 2, 2010 The late 1971 PL 521 pickups with an evaporative emission system did have a fuel return line. Most 521 pickups did not. I don't think it was a return line, but fed evaporated gas fumes forward to the PCV system. Pretty sure return fuel lines weren't used until '75 when the L20B were used. It was to circulate cool fuel past the carb to prevent vapor lock from the increased under hood temperatures. What is the best idle adjustment on a Hitachi? Or How do I do it? On the valve cover side of the Hitachi there are two screw adjustments. The one to the rear and part of the throttle is the idle speed and it simply moves the position at which the throttle rests against it. The other one is in the base of the carburetor and increases or decreases the amount of fuel flowing through the idle circuit. As Daniel said, the ignition timing and the valve lash need to be set first, but also you need to be able to idle to set the timing too, so you may have to set it first, do the timing and come back later and re set the idle. On a thoroughly warm engine, set the idle speed as low as possible but keep running. If you turn the idle mixture in until it stumbles, then out till it stumbles, then select a spot about half way between where it runs smooth and even, don't worry if it revs up slightly. Now adjust the idle down and begin again, turning the mixture screw in then out to find a smooth spot in the middle and then turning the idle speed down. Keep repeating until any adjustment does not improve the idle quality. If you can't get the idle down low enough and can't be turned below 1,200 RPMs without it quitting then the idle cut solenoid may not be working. Without it there is no gas getting to the idle circuit. It will be running on the primary barrel and this will be a wasted effort until this is corrected. Quote Link to comment
sdsurf Posted January 2, 2010 Author Report Share Posted January 2, 2010 If you can't get the idle down low enough and can't be turned below 1,200 RPMs without it quitting then the idle cut solenoid may not be working. Without it there is no gas getting to the idle circuit. It will be running on the primary barrel and this will be a wasted effort until this is corrected. Where is the idle cut solenoid? Is this electronic? Quote Link to comment
datzenmike Posted January 2, 2010 Report Share Posted January 2, 2010 It's electric. (but now a days anything with electricity is 'electronic') When the ignition is ON the solenoid is ON and allows fuel to pass into the idle circuit. When the key is turned off it closes and helps shut the motor dow faster by removing the fuel source. This prevents hot motor 'run on'. The idle cut solenoid is the hexagonal thing with the Red wire coming out of it. Turn the ignition on/off/on/off and if it's working you'll hear a clicking sound coming from it. Quote Link to comment
I'm BLUE Posted January 2, 2010 Report Share Posted January 2, 2010 It's electric. (but now a days anything with electricity is 'electronic') When the ignition is ON the solenoid is ON and allows fuel to pass into the idle circuit. When the key is turned off it closes and helps shut the motor dow faster by removing the fuel source. This prevents hot motor 'run on'. The idle cut solenoid is the hexagonal thing with the Red wire coming out of it. Turn the ignition on/off/on/off and if it's working you'll hear a clicking sound coming from it. Agreed , datzenmike is absolutely right :D ! The ide cut solenoid is designed to keep your vehicle from "dieseling" ( to keep engine from running after the fact once key is in off position ) In my experience with a carbureted subaru , faulty wiring to the idle cut solenoid had bad electrical contact one day , and I could barely keep the engine running without pumping it ??? ( at least above idle all the time ) I have very little experience with these solenoids , and datzenmike seems to be hitting very close to home on this ! Quote Link to comment
DanielC Posted January 2, 2010 Report Share Posted January 2, 2010 DatsunMike, Or do I need to address you as KingRat? You very well could be right, about a fuel return line on a late 521. I have three 521 trucks, all were drivers at one time, but one is close, one is a parts truck, and one has some potential. I refer to the trucks as a 1969, a 1970, and a 1971. All three had L-16 engines in them. The first 521 I got was the 1971. This is the one that I believe has a fuel return line on it. It is the only one of my 521 trucks that came with the evaporative system on it. It did have the valve on the right inner fender hooked up to a small pipe attached to the large pipe that the PVC valve hose goes to, for the evaporative emissions control. It also had a fitting/valve assembly for the fuel inlet to the carb that has a place for two fuel hoses to attach to. My understanding of this fitting/valve assembly is that above a certain temperature, a valve inside this fitting opens up and allows some gas to bypass the carb, and return to the tank, to prevent vapor lock, similar to what you described for the later than mine trucks. Both of my earlier 521 trucks did not have an evaporative control system, nor did they have the fuel fitting/valve assembly. They just had a standard banjo to fuel hose inlet fitting on the carburettor. Here is a picture of the fitting/Valve assembly that was on the 1971 521 Carburettor. Quote Link to comment
datzenmike Posted January 2, 2010 Report Share Posted January 2, 2010 The '79 620 actually used the idle cut as part of a fuel shut off system. When decelerating fuel is still being sucked into the motor through the idle circuit and not being burned properly. The system used a top gear, neutral, clutch and a vacuum switch. As long as you were in top gear, clutch out and high manifold vacuum the idle cut was shut off so no fuel flowed to the idle circuit. This reduced emissions and saved fuel too. Quote Link to comment
sdsurf Posted January 3, 2010 Author Report Share Posted January 3, 2010 It's electric. (but now a days anything with electricity is 'electronic') When the ignition is ON the solenoid is ON and allows fuel to pass into the idle circuit. When the key is turned off it closes and helps shut the motor dow faster by removing the fuel source. This prevents hot motor 'run on'. The idle cut solenoid is the hexagonal thing with the Red wire coming out of it. Turn the ignition on/off/on/off and if it's working you'll hear a clicking sound coming from it. I don't have that. My Hitachi is the early 326 (?) without the idle cutoff. But it does have a funky electric deal on the mount for the throttle (mount bolts to the right side of carb). what is this for? Quote Link to comment
DanielC Posted January 3, 2010 Report Share Posted January 3, 2010 The 521 pickups have two sets of points that they used for emission control. One set of points is retarded from the other. Most of the time, the truck runs on the advanced set of points. The retarded set is used only when at part throttle, third gear, clutch not depressed. One switch on the carb tells the system your throttle is at idle, and in third gear, you run on the advanced pointsm, until the throttle is opened a little. The other switch on the carb tells the system when you are at wide open throttle, and again you run on the advanced set of points. Quote Link to comment
CrabDragon Posted January 3, 2010 Report Share Posted January 3, 2010 I was having major fuel problems with my 521. Make sure to check all lines and it would be best to replace all stock rubber lines because they will be cracked. Trust me. Plus thats one less thing to worry about in the future. Unless you are going for the stock show car look. I also replaced the carb with a Webber and now it runs great. I love it. Disconnect the fuel line at the fuel filter, that goes to the gas tank. Blow air back to the gas tank, and see if there is some kind of clog at the fuel pick up in the tank. If there is, this works as a temporary fix, but you need to clean out the tank, probably by dropping it, and dumping any crud out, and rinsing it out. Quote Link to comment
RoadRace Posted January 4, 2010 Report Share Posted January 4, 2010 SdSurf - the vent for the carb will be either a short vertical or vertical facing pipe within the sealed venturi/booster/air intake area or a horizontal one that looks like its too big for a vacuum line and has no vacuum on it when running - usually hooked to a carbon canister or other emmission 'dump zone'. it is NOT a return line - that is very different. On the DOHC webers, the vent is that big hole on the front of the carb on the float chamber above the venturi's. the hitachi carbs i see are usually in the trunk of the cars i buy - sorry about the lack of Hitachi-specific data here. the fuel tank will have a vent as well - not sure about the trucks, the 510 had a seperate venting tank in the trunk, above the fuel tank under the rear window cowl. i just vent the tank downward outside the body on the racecar. the fuel pump will have a very small slot cast into the atmosphere side of the pump diaphragm along the split line. this can usually get block with little consequence, however the fuel tank and carb vents, if blocked, will give you the symptoms you're describing. As the fule leaves the carb, air must replace it and vice versa, other wise there will be positive or negaitve pressure in the float bowl or the furl tank. the pump either can't push enough fuel in to the float bowl, or it can't pull enough from the tank to keep up with the supply. checking the venting in your fuel system is exacly the same as checking for grounds in your electrical system - first thing to do! Quote Link to comment
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