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454 Fuel Pump/Pressures

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CaptJoe3

Member
I have twin 1994 Crusader 7.4 TBIs and am dealing with stall/no start issues on Port engine. We're reading low fuel pressure 5-8 psi. Manual says 16psi min and 20/22 max psi. Why are many on this forum posting their fuel pressure reading "perfect 12psi? And fuel pump pressure is 14-18psi? Any recommendations for best source for 454 electric pump? Prices are all over the place?
 
CaptJoe3 said:
I have twin 1994 Crusader 7.4 TBIs and am dealing with stall/no start issues on Port engine. We're reading low fuel pressure 5-8 psi. Manual says 16psi min and 20/22 max psi. Why are many on this forum posting their fuel pressure reading "perfect 12psi? And fuel pump pressure is 14-18psi? Any recommendations for best source for 454 electric pump? Prices are all over the place?
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Actually fuel pump tested at 30 psi using diesel. Didn't have gas in shop. Will test using gas later today.
 
Do you know why there are so many different opinions on fuel pressures for the pumps on these engines? The specs from the Crusader manual state 16 psi to 20 psi (maybe its 22?) But folks refer to 45 psi as low pressure pumps. Many of the pumps on the market for Crusader don't even state the pressure ratings so you don't know what you're getting.
 
1st, I WOULD NOT buy any Amazon/Chineesium fuel parts. Buy OEM. OEM will be the correct pressure.
2nd, you have a perfectly good engine 3 feet away. You can certainly swap parts 1 at a time until you find the bad 1.
 
OEM
Always if you can find it! I have 2 spare Carter marine fuel pumps for my old 4.3 in the garage. The one thats been on it for the past 8 years is a Sierra that was actually fine passed all the fuel pumps tests in the OMC factory shop manual and puts out 5.5 psi. Just right for a carb engine. So once in a while decent aftermarket works out fine. Only bought that one cause I couldn’t get a Carter when I needed it.
 
louc said:
OEM
Always if you can find it! I have 2 spare Carter marine fuel pumps for my old 4.3 in the garage. The one thats been on it for the past 8 years is a Sierra that was actually fine passed all the fuel pumps tests in the OMC factory shop manual and puts out 5.5 psi. Just right for a carb engine. So once in a while decent aftermarket works out fine. Only bought that one cause I couldn’t get a Carter when I needed it.
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Same here. One of my 1991 Crusader 350 small blocks has the original fuel pump on it and the other has a Carter electric pump. Works great with Rochester quadrajet carbs. Have a spare Carter in case the mechanical on the other engine packs it in. Both pumps bought at NAPA
 
CaptJoe3 said:
Do you know why there are so many different opinions on fuel pressures for the pumps on these engines? The specs from the Crusader manual state 16 psi to 20 psi (maybe its 22?) But folks refer to 45 psi as low pressure pumps. Many of the pumps on the market for Crusader don't even state the pressure ratings so you don't know what you're getting.
Click to expand...
The mid 1990's were very dynamic regarding GM marine engine configurations...mostly driven by the desire to get EFI into the marine domain. The TBI versions, as best as I can tell, came in two flavors - the big difference being the operating fuel pressure.

The sad part is the TBI units had a very short production run (a few years)...so the total number of units made was small and the support demand was proportional. so the remaining supplier base, for parts and knowledge, continues to shrink. Parts will likely be available for a while but at an increasing cost.
 
louc said:
OEM
Always if you can find it! I have 2 spare Carter marine fuel pumps for my old 4.3 in the garage. The one thats been on it for the past 8 years is a Sierra that was actually fine passed all the fuel pumps tests in the OMC factory shop manual and puts out 5.5 psi. Just right for a carb engine. So once in a while decent aftermarket works out fine. Only bought that one cause I couldn’t get a Carter when I needed it.
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Late getting back but anything less than 11 psi wont run these engines
 
AllDodge said:
With fuel pump output pressure at 30 psi, I would look at the regulator which is part of the TBI
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Yes, we replace fuel pressure regulator which improved fuel pressure to 10-11psi. Still would not run. Replaced with a spare fuel pump that tested 30 psi on the bench. Now have 20ish psi engine runs but idle is quite rough. Working on that.
 
makomark said:
The mid 1990's were very dynamic regarding GM marine engine configurations...mostly driven by the desire to get EFI into the marine domain. The TBI versions, as best as I can tell, came in two flavors - the big difference being the operating fuel pressure.

The sad part is the TBI units had a very short production run (a few years)...so the total number of units made was small and the support demand was proportional. so the remaining supplier base, for parts and knowledge, continues to shrink. Parts will likely be available for a while but at an increasing cost.
Click to expand...
 
Sadly, I'm finding this out. From what I have been able to determine, the first generation TBI, aka MEFI-1 came out 1992/1993 and ran through 1995, when the MEFI-2 came out and ran through 1997, maybe '99. So it's important to start with Crusader SN. Mine, as it turns out are 1993 and 1994 respectively, the '94 being the Starboard engine and Reverse Rotation. Getting parts is a real challenge. I have found that some of the electronic sensors (MAP, IAC, etc) available from parts stores are identical to the "Crusader" branded parts and are adequate and much less expensive and they come from reliable brand manufacturers eg Delco, Standard, and others and since they are sealed, they meet the ABYC and CG requirement. Fuel pumps, on the otherhand, I'm not so sure about their reliability. Did Crusader change pumps on the 7.4 when they went to the multiport injection? I know that Carter made the original "gerotor" electric fuel pumps but discontinued, I suppose when Crusader stopped making the 454. (They, PCM, are still making 8.1 big blocks. Do you know if those engines use the same fuel pumps as the 7.4 TBi? There are many OEM 454 TBi pumps on the market, most, if not all are Chinese. From what I can tell, the Sierra pumps are identical to the off branded OEM pumps found on Amazon/eBay etc. My Crusader service manual shows a part number of #23232 Fuel Pump Assembly, but all of the replacement pumps (Marine Engine included) show #23234 for the same item, but nowhere is there an explanation of the difference. If you can find an answer, please share. A couple of years ago a poster said he just put on a Carter pump (don't have the part # handy) that a Carter Engineering representative specifically told me was for automotive use and as we all know that's a KABOOM just waiting to happen! Thanks for all the knowlege you share on this forum!
 
AllDodge said:
Most HP fuel pumps will read 60 psi on the bench
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That's way too high. Once again, what is the definition of High pressure vs. Low pressure? I see some requirements for High pressure and presume that is above 30 psi. The spec for the TBI is 16-22 psi. Is that considered High or Low? I can't find any kind of reference. Most pumps are referred to in this way, are not defined with a psi spec.
 
CaptJoe3 said:
That's way too high. Once again, what is the definition of High pressure vs. Low pressure? I
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This is from Merc Manual 16 which is same as Manuals in later years. This is why if the test is done it needs to be disconnected from the regulator because if 50 psi is exceeded it can damaged the Reg

1793135174194.png
 
willow said:
Same here. One of my 1991 Crusader 350 small blocks has the original fuel pump on it and the other has a Carter electric pump. Works great with Rochester quadrajet carbs. Have a spare Carter in case the mechanical on the other engine packs it in. Both pumps bought at NAPA
Click to expand...
Morning Willow, are the NAPA pumps marine grade?
 
CaptJoe3 said:
Sadly, I'm finding this out. From what I have been able to determine, the first generation TBI, aka MEFI-1 came out 1992/1993 and ran through 1995, when the MEFI-2 came out and ran through 1997, maybe '99. So it's important to start with Crusader SN. Mine, as it turns out are 1993 and 1994 respectively, the '94 being the Starboard engine and Reverse Rotation. Getting parts is a real challenge. I have found that some of the electronic sensors (MAP, IAC, etc) available from parts stores are identical to the "Crusader" branded parts and are adequate and much less expensive and they come from reliable brand manufacturers eg Delco, Standard, and others and since they are sealed, they meet the ABYC and CG requirement. Fuel pumps, on the otherhand, I'm not so sure about their reliability. Did Crusader change pumps on the 7.4 when they went to the multiport injection? I know that Carter made the original "gerotor" electric fuel pumps but discontinued, I suppose when Crusader stopped making the 454. (They, PCM, are still making 8.1 big blocks. Do you know if those engines use the same fuel pumps as the 7.4 TBi? There are many OEM 454 TBi pumps on the market, most, if not all are Chinese. From what I can tell, the Sierra pumps are identical to the off branded OEM pumps found on Amazon/eBay etc. My Crusader service manual shows a part number of #23232 Fuel Pump Assembly, but all of the replacement pumps (Marine Engine included) show #23234 for the same item, but nowhere is there an explanation of the difference. If you can find an answer, please share. A couple of years ago a poster said he just put on a Carter pump (don't have the part # handy) that a Carter Engineering representative specifically told me was for automotive use and as we all know that's a KABOOM just waiting to happen! Thanks for all the knowlege you share on this forum!
Click to expand...
I am certain both Crusader and Marine Power had TBI equipped engines that had at least two different operating fuel pump pressures. That they may map to a specific version of MEFI controller is coincidence, not a consequence. (Marine Power refers to these as the 9 and 16 PSI TBI systems.)

The Multiport systems typically run with much higher operating pressures. It is here where you will see several versions of the two pump delvery systems (which introduces the HIGH and LOW pressure pump designators).

most pumps have a lift rating and a volume and pressure chart though they are hard to find. Most provide minimum values in their operating environments. As long as all of the parts "match" things perform as expected - when something falls short, performance suffers at a minimum - major damage in the worst case...
 
missnancy said:
Morning Willow, are the NAPA pumps marine grade?
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I believe so, I have the part numbers buried in the boat and up here in the Great White North, the boat is locked up and in "winter"storage.:LOL: Will check when I can get access to the boat in the Spring.....been running that particular engine for about 10 years with the Carter pump and no problems.
 
A couple of guys over at iboats actually converted their engines back to carbs due to problems sourcing fuel injection parts all these years later. While it seems like a backward step, you can always get parts for a Holley or Edelbrock marine carb, I can even get just about anything I could need for a Quadrajet that's 38 years old! And these will run on a low pressure electric fuel pump (5-6 psi) just fine.
New carbs, both Holley and Edelbrock are widely available. 4bbl cast iron intakes can be found used as well.
 
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