GnatGoSplat Posted July 8, 2008 Report Share Posted July 8, 2008 For the first time in 9-years, my 89 Cutlass left me stranded. For the first time ever, it left me stranded in the turn lane of a busy intersection in rush hour traffic! So embarrassing! Anyway, the FPR went bad. It happened just 9-months after installing a Walbro 255lph high pressure fuel pump. Think it could be the fuel pump damaged the FPR, or just a coincidence? The FPR is nearly 20yrs old and has 207k miles on it. From my understanding, the fuel pump rating of 255lph is just a max, the FPR will only allow up to 40-something PSI or whatever spec is to get to the injectors, and the rest will just be returned to the tank. So as far as I know, this shouldn't affect internal pressure of the FPR. However, FPR going out just 9-months after installing the Walbro makes me wonder. Thoughts? Any FPR experts? Quote Link to comment Share on other sites More sharing options...
Brian P Posted July 8, 2008 Report Share Posted July 8, 2008 I'd just change it out. A lot of TGP guys are running that pump and I haven't heard any horror stories about the FPR. The fact that you got 209k out of it, that's not bad. What'd it do, dump a lot of fuel into the engine, or cut fuel altogether? Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 8, 2008 Author Report Share Posted July 8, 2008 It dumped fuel, I pulled the vacuum hose off of it and fuel poured out. I'm guessing the diaphragm inside ruptured. I've been debating whether I ought to use a PWM motor speed controller to reduce power going to the fuel pump. I HATE being stranded, blocking traffic in a busy intersection! Quote Link to comment Share on other sites More sharing options...
Brian P Posted July 8, 2008 Report Share Posted July 8, 2008 I forgot to specify when I wrote "change it out" I meant the FPR, not the pump That must have been a lot of fuel. But if you'd use the PWM controller, wouldn't the low power reduce the life of the pump? Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 8, 2008 Author Report Share Posted July 8, 2008 I think it won't if it's a PWM controller... PWM = Pulse Width Modulation which means to reduce the speed, it pulses the pump very quickly on and off (several hundred or thousand times per second) keeping voltage the normal 12-14V. They are very electrically efficient and it seems some cars have a PWM fuel pump controller from the factory. The other method would simply be to reduce voltage using a resistor... this is what the gen 2 W-bodies use. It decreases voltage, causing the coil to run hotter and reducing pump life. At the same time, the resistor dissipates the waste current as heat, eventually causing resistor failure and no power to the pump. This is why a lot of gen 2 W-body owners bypass the resistor. I would just do the simple thing and replace the FPR without worrying about reducing pump flow, but being stranded sucked so bad I REALLY don't want that to ever happen again. Plus, having the car towed almost always results in damage to car and in this case, even damage to the house! The tow truck driver accidentally smashed a brick on our house trying to maneuver the tow truck into a position where he could get the car into the garage. Quote Link to comment Share on other sites More sharing options...
Brian P Posted July 8, 2008 Report Share Posted July 8, 2008 I see what you mean. If it were me I'd replace the FPR, then carry a tube cap with a fuel-line clamp should it ever happen again, then I could get it home Maybe the TGP guys have knowledge of it. I've never heard of the Walbro pump causing FPR failures but who knows. At the mileage you had, I think the FPR just had enough. These things break with the stock fuel pump quite often too! Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 8, 2008 Author Report Share Posted July 8, 2008 Would a cap work to limp it home? I had wondered about that, I might have to try it when I get home!!! Yeah, it could have just been coincidence. Kind of like when I changed the head gaskets, a coil died at that exact time and I thought I'd screwed up the job. I'll just replace the FPR and not worry about it, especially if that cap trick works! I was looking at FPRs on eBay, most have the fittings in them, but I found one for much cheaper that doesn't. Do they just thread in, or does it require special tools to R&R the fittings? I think the last one I bought for the TGP had fittings already in it. Quote Link to comment Share on other sites More sharing options...
Brian P Posted July 8, 2008 Report Share Posted July 8, 2008 you're asking me to dig into the gen-II V6 brain archives honestly I never changed a Gen-2 FPR but rockauto.com has the Standard FPR for $66+ ship -5% that has the fittings on it. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 8, 2008 Author Report Share Posted July 8, 2008 Yeah, the one on eBay w/out fittings is <$30 shipped! I'm a cheap bastard! I'll pull it off and see if those fittings come off or not. Quote Link to comment Share on other sites More sharing options...
Brian P Posted July 8, 2008 Report Share Posted July 8, 2008 hopefully! It wouldn't surprise me if they're just in there with O-rings and threaded in. Quote Link to comment Share on other sites More sharing options...
Bake82 Posted July 9, 2008 Report Share Posted July 9, 2008 I can send you one from my parts 88. I'd charge just shipping and could get it out tomorrow if you want? It's got 250,000 km....don't know if it owuld interest you or not. Let me know! Quote Link to comment Share on other sites More sharing options...
BXX Posted July 9, 2008 Report Share Posted July 9, 2008 Gen2 660s arent uncommon to have the FPR fail.. Actually they are about as common to fail as much as the FPR diaphram on TPI engines... Yes, I had one fail... The diaphram just gets old and cant handle the pressure anymore.. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 10, 2008 Author Report Share Posted July 10, 2008 I can send you one from my parts 88. I'd charge just shipping and could get it out tomorrow if you want? It's got 250,000 km....don't know if it owuld interest you or not. Let me know! Thanks for the offer, but I'd prefer one with less mileage! I was curious what would happen with the FPR capped off, the fuel pressure keeps increasing! Just two turns of the key and the rails were at 80psi! I guess when this kind of thing happens, limping the car home with a cap on the FPR probably won't work out too well. Sure glad it's not the fuel pump though, I HATE changing those. Quote Link to comment Share on other sites More sharing options...
Brian P Posted July 10, 2008 Report Share Posted July 10, 2008 I can send you one from my parts 88. I'd charge just shipping and could get it out tomorrow if you want? It's got 250,000 km....don't know if it owuld interest you or not. Let me know! Thanks for the offer, but I'd prefer one with less mileage! I was curious what would happen with the FPR capped off, the fuel pressure keeps increasing! Just two turns of the key and the rails were at 80psi! I guess when this kind of thing happens, limping the car home with a cap on the FPR probably won't work out too well. Sure glad it's not the fuel pump though, I HATE changing those. 80! Nice! It should still run though, just rich I'm running my injectors at 55psi, what's another 25 Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 10, 2008 Author Report Share Posted July 10, 2008 80 was just after 2 key flicks, no telling how high it could have gone up to with the pump running constantly! I was afraid to see if it would run, I didn't want to damage any seals or hurt the injectors or pump (the sound of the pump was significantly higher pitched at very high pressure). It was holding pressure with the port plugged, I guess the way the FPR died, the return line is completely blocked. There was a lot of fuel settled in the ribs of the air intake tube as well. The car won't crank, I was thinking I just cranked it so much I wore down the battery. I wonder if it could have become so badly flooded that it got hydrolocked? I've had a bad FPR before, but it sure wasn't this bad! Quote Link to comment Share on other sites More sharing options...
Brian P Posted July 10, 2008 Report Share Posted July 10, 2008 yeah that's a bad death. You may have to crank that motor with the spark plugs out and fuel pump & ignition disabled if it flooded that bad! Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 22, 2008 Author Report Share Posted July 22, 2008 I got the car back together today. Is the FPR supposed to let some fuel be returned even if there's no vacuum? I'm seeing 65 psi after the pump runs for a few seconds and it keeps going up. When I start the car, my fuel pressure gauge goes nuts, swinging from about 75-100psi several times a second. I tried disconnecting the fuel return, and there is NOTHING being returned. I even disconnected it at the rail. Not one drop. Can lack of vacuum cause this, or is the FPR supposed to always be letting some fuel be returned? How much vacuum should an FPR see? I'm completely confused as to what's going on here, as I thought vacuum or not, some fuel should be returned. Is there any other explanation other than I got a bad FPR from eBay? Quote Link to comment Share on other sites More sharing options...
99RegalGS Posted July 22, 2008 Report Share Posted July 22, 2008 Yes, the fuel pressure regulator should have fuel being returned even if there is no vacuum. IIRC there's only suppose to be a 4-5 psi difference from full vacuum to no vacuum. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 22, 2008 Author Report Share Posted July 22, 2008 Yeah, that's what I thought, the spring inside should allow anything in excess of about ~40psi to bleed off to the return line, right? Just in case, I tested my fuel pressure gauge on the 94 Cutlass and it's fine. Seeing as how both the original bad FPR and my new replacement were not returning any fuel, I thought maybe something broke inside the rails, but there is no blockage in the rails. Fuel pumped into their inlets comes out with no resistance from their outlets. So the rails are okay, there is no blockage on the return line, that leaves only the FPR, correct? In that case, I guess my new eBay FPR is crap. Quote Link to comment Share on other sites More sharing options...
Brian P Posted July 22, 2008 Report Share Posted July 22, 2008 Yeah I'm guessing the cheapo FPR is no good too Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 22, 2008 Author Report Share Posted July 22, 2008 I guess that's what I get for trying to save $40! Quote Link to comment Share on other sites More sharing options...
ManicMechanic Posted July 22, 2008 Report Share Posted July 22, 2008 Yeah, unfortunately most of those 'parts' on ebay are Chinese crap I've found. I'm on my THIRD power window motor in the van. Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted July 23, 2008 Report Share Posted July 23, 2008 Interesting Thread. Quote Link to comment Share on other sites More sharing options...
ismellrealbad Posted July 24, 2008 Report Share Posted July 24, 2008 Interesting Thread. hella x2 x3 on bad FPR Im pretty sure theres supposed to be fuel returned at all time as well. anything over 45psi is too high Quote Link to comment Share on other sites More sharing options...
1990lumina Posted July 24, 2008 Report Share Posted July 24, 2008 The 80 or so psi is called deadheading the pump. It's okay to do, but NOT FOR LONG. It's one of many tests done to fuel systems, but it should be done long enough to see max pressure and then let it off - especially in a high mileage car something will explode lol. Quote Link to comment Share on other sites More sharing options...
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